Access the full text.
Sign up today, get DeepDyve free for 14 days.
Melissa Coolong-Chaffin, Mickey Crothers, J. Goodman, Christopher Hagan, Jarrod Hines, S. Jackson, David Jewett, Kevin Klatt, Carla Lagorio, Mary Leibham, David Leland, J. Muehlenkamp, Jennifer Parker, David Sparkman, Mary Tusing, C. Vriesema (1929)
PsychologyThe Indian Medical Gazette, 65
J. Shaw, I. Hunt, S. Flynn, J. Meehan, J. Robinson, Harriet Bickley, R. Parsons, Kerry McCann, J. Burns, T. Amos, N. Kapur, L. Appleby (2006)
Rates of mental disorder in people convicted of homicideBritish Journal of Psychiatry, 188
Jennifer Todd, Gill Green, M. Harrison, B. Ikuesan, C. Self, D. Pevalin, Alex Baldacchino (2004)
Social exclusion in clients with comorbid mental health and substance misuse problemsSocial Psychiatry and Psychiatric Epidemiology, 39
Christopher Hewitt (2002)
Understanding terrorism in America
Reid Melo, A. Hempel, Thomas Gray, K. Mohandie, Andrew Shiva, Thomas Richards (2004)
A comparative analysis of North American adolescent and adult mass murderers.Behavioral sciences & the law, 22 3
R. Kessler, W. Chiu, Olga Demler, K. Merikangas, E. Walters (2005)
Prevalence, severity, and comorbidity of 12-month DSM-IV disorders in the National Comorbidity Survey Replication.Archives of general psychiatry, 62 6
J. Simon (2013)
Lone Wolf Terrorism: Understanding the Growing Threat
E. Elbogen, Sally Johnson (2009)
The intricate link between violence and mental disorder: results from the National Epidemiologic Survey on Alcohol and Related Conditions.Archives of general psychiatry, 66 2
P. Gill, E. Corner (2013)
Disaggregating Terrorist Offenders: Implications for Research and PracticeCriminology and public policy, 12
(2012)
Sampling methods and sample size calculation for the SMART methodology
F. Fernández (1980)
[Psychology of terrorism].Anales de la Real Academia Nacional de Medicina, 97 2
J. Meloy, A. Hempel, K. Mohandie, Andrew Shiva, B. Gray (2001)
Offender and offense characteristics of a nonrandom sample of adolescent mass murderers.Journal of the American Academy of Child and Adolescent Psychiatry, 40 6
K. Abram, L. Teplin (1991)
Co-occurring disorders among mentally ill jail detainees. Implications for public policy.The American psychologist, 46 10
R. Borum (2013)
Informing Lone‐Offender InvestigationsCriminology and public policy, 12
Jeff Gruenewald, S. Chermak, Joshua Freilich (2013)
Overview of: “Distinguishing ‘Loner’ Attacks from Other Domestic Extremist Violence: A Comparison of Far-Right Homicide Incident and Offender Characteristics”: Loner Attacks and Domestic ExtremismCriminology and public policy, 12
S. Chermak, Joshua Freilich, J. Simone (2010)
Surveying American State Police Agencies About Lone Wolves, Far-Right Criminality, and Far-Right and Islamic Jihadist Criminal CollaborationStudies in Conflict & Terrorism, 33
J. Horgan (2005)
The Psychology of Terrorism
N. Ferguson, M. Burgess, Ian Hollywood (2008)
Crossing the Rubicon: Deciding to Become a Paramilitary in Northern IrelandInternational Journal of Conflict and Violence, 2
Keith Farrington (1986)
The application of stress theory to the study of family violence: Principles, problems, and prospectsJournal of Family Violence, 1
M. Sageman (2004)
Understanding terror networks.International journal of emergency mental health, 7 1
Jeff Gruenewald, S. Chermak, Joshua Freilich (2013)
Distinguishing “Loner” Attacks from Other Domestic Extremist ViolenceCriminology and public policy, 12
Sarah Hauffe, Louise Porter (2009)
An interpersonal comparison of lone and group rape offencesPsychology, Crime & Law, 15
N. Singleton, R. Gatward, H. Meltzer (1998)
Psychiatric morbidity among prisoners in England and Wales : the report of a survey carried out in 1997 by Social Survey Division of the Office for National Statistics on behalf of the Department of Health
R. Fein, Bryan Vossekuil (1999)
Assassination in the United States: an operational study of recent assassins, attackers, and near-lethal approachers.Journal of forensic sciences, 44 2
K. Douglas, Laura Guy, S. Hart (2009)
Psychosis as a risk factor for violence to others: a meta-analysis.Psychological bulletin, 135 5
Fernando Reinares (2004)
Who Are the Terrorists? Analyzing Changes in Sociological Profile among Members of ETAStudies in Conflict & Terrorism, 27
K. Kendler, L. Karkowski, C. Prescott (1999)
Causal relationship between stressful life events and the onset of major depression.The American journal of psychiatry, 156 6
M. Crenshaw (1981)
The Causes of TerrorismComparative politics, 13
R. Agnew (2010)
A general strain theory of terrorismTheoretical Criminology, 14
(2005)
The mind of the terrorist: A review and critique of psychological approaches
(2010)
ICD-10: International statistical classification of diseases and related health problems (10th review)
K. Hickle, D. Roe-Sepowitz (2010)
Female juvenile arsonists: An exploratory look at characteristics and solo and group arson offencesLegal and Criminological Psychology, 15
M. Ouzir (2013)
Impulsivity in schizophrenia: A comprehensive updateAggression and Violent Behavior, 18
Ethan Mesquita (2005)
The Quality of TerrorAmerican Journal of Political Science, 49
R. Spaaij (2010)
The Enigma of Lone Wolf Terrorism: An AssessmentStudies in Conflict & Terrorism, 33
K. Langhoff, D. Roe-Sepowitz (2007)
Female Juvenile Arsonists
C. Bijleveld, J. Hendriks (2003)
Juvenile Sex Offenders: Differences between Group and Solo OffendersPsychology, Crime & Law, 9
C. McCauley, S. Moskalenko, B. Son (2013)
Characteristics of Lone-Wolf Violent Offenders: a Comparison of Assassins and School AttackersPerspectives on terrorism, 7
A. Roberts, K. McLaughlin, Kerith Conron, K. Koenen (2011)
Adulthood stressors, history of childhood adversity, and risk of perpetration of intimate partner violence.American journal of preventive medicine, 40 2
J. Swanson, C. Holzer, V. Ganju, R. Jono (1990)
Violence and psychiatric disorder in the community: evidence from the Epidemiologic Catchment Area surveys.Hospital & community psychiatry, 41 7
(2011)
Islamist terrorism: The British connections
T. Scheid, Tony Brown (2009)
A handbook for the study of mental health : social contexts, theories, and systems
A. Silke (2008)
Becoming a Terrorist
D. Elisha, D. Castle, B. Hocking (2006)
Reducing social isolation in people with mental illness: the role of the psychiatrist.Australasian psychiatry : bulletin of Royal Australian and New Zealand College of Psychiatrists, 14 3
M. Anderson (1997)
Mental illness and criminal behaviour: a literature review.Journal of psychiatric and mental health nursing, 4 4
Roger Peters (2013)
Co-occurring disorders
J. Coid, S. Ullrich, R. Keers, P. Bebbington, B. DeStavola, C. Kallis, Min Yang, D. Reiss, Rachel Jenkins, P. Donnelly (2013)
Gang membership, violence, and psychiatric morbidity.The American journal of psychiatry, 170 9
Daryl Higgins, S. Bailey, Julian Pearce (2005)
Factors associated with functioning style and coping strategies of families with a child with an autism spectrum disorderAutism, 9
D. James, P. Mullen, J. Meloy, M. Pathé, F. Farnham, L. Preston, B. Darnley (2007)
The role of mental disorder in attacks on European politicians 1990–2004Acta Psychiatrica Scandinavica, 116
P. Thoits (1983)
Multiple identities and psychological well-being: a reformulation and test of the social isolation hypothesis.American sociological review, 48 2
L. Teplin (1984)
Criminalizing mental disorder. The comparative arrest rate of the mentally ill.The American psychologist, 39 7
W. Holcomb, P. Ahr (1988)
Arrest rates among young adult psychiatric patients treated in inpatient and outpatient settings.Hospital & community psychiatry, 39 1
S. Fazel, J. Danesh (2002)
Serious mental disorder in 23 000 prisoners: a systematic review of 62 surveysThe Lancet, 359
Doug McAdam (1986)
Recruitment to High-Risk Activism: The Case of Freedom SummerAmerican Journal of Sociology, 92
(2012)
MAPPA guidance: Version 4 Retrieved from http:// www.justice.gov.uk/downloads/offenders/mappa/mappa-guidance-2012-part1 Profiles in terror
P. Gill, J. Horgan, P. Deckert (2013)
Bombing Alone: Tracing the Motivations and Antecedent Behaviors of Lone-Actor Terrorists*,†,‡Journal of Forensic Sciences, 59
J. Rabe‐Jabłońska (1993)
[Affective disorders in the fourth edition of the classification of mental disorders prepared by the American Psychiatric Association -- diagnostic and statistical manual of mental disorders].Psychiatria polska, 27 3
J. Post, E. Sprinzak, L. Denny (2003)
The terrorists in their own words: Interviews with 35 incarcerated Middle Eastern terrorists**This research was conducted with the support of the Smith Richardson Foundation.Terrorism and Political Violence, 15
R. Borum, R. Fein, Bryan Vossekuil (2012)
A dimensional approach to analyzing lone offender terrorismAggression and Violent Behavior, 17
G. Saxe, B. Kolk, Ross Berkowitz, G. Chinman, Kathryn Hall, G. Lieberg, Jennifer Schwartz (1993)
Dissociative disorders in psychiatric inpatients.The American journal of psychiatry, 150 7
J. Post (1991)
Saddam Husseim of Iraq: a political psychology profilePolitical Psychology, 12
C. Scott, P. Resnick (2006)
Violence risk assessment in persons with mental illnessAggression and Violent Behavior, 11
Tim Krieger, Daniel Meierrieks (2011)
What causes terrorism?Public Choice, 147
Wilfried Rasch (1979)
Psychological dimensions of political terrorism in the Federal Republic of Germany.International journal of law and psychiatry, 2 1
Christine Montross (2017)
Mental Illness and the Criminal Justice System.The New England journal of medicine, 376 2
V. Hiday (1995)
The social context of mental illness and violence.Journal of health and social behavior, 36 2
M. Krakowski, J. Volavka, D. Brizer (1986)
Psychopathology and violence: a review of literature.Comprehensive psychiatry, 27 2
(1990)
The readiness to kill and die: Suicidal terrorism in the Middle East Origins of terrorism
Bruce Link, A. Stueve (1994)
Psychotic Symptoms and the Violent/Illegal Behavior of Mental Patients Compared to Community Controls
P. Lowenstein (2009)
Crossing the RubiconNature Biotechnology, 27
Janet Williams (2013)
Diagnostic and Statistical Manual of Mental Disorders
Law and Human Behavior © 2014 American Psychological Association 2015, Vol. 39, No. 1, 23–34 0147-7307/15/$12.00 http://dx.doi.org/10.1037/lhb0000102 Emily Corner and Paul Gill University College London We test whether significant differences in mental illness exist in a matched sample of lone- and group-based terrorists. We then test whether there are distinct behavioral differences between lone-actor terrorists with and without mental illness. We then stratify our sample across a range of diagnoses and again test whether significant differences exist. We conduct a series of bivariate, multivariate, and multinomial statistical tests using a unique dataset of 119 lone-actor terrorists and a matched sample of group-based terrorists. The odds of a lone-actor terrorist having a mental illness is 13.49 times higher than the odds of a group actor having a mental illness. Lone actors who were mentally ill were 18.07 times more likely to have a spouse or partner who was involved in a wider movement than those without a history of mental illness. Those with a mental illness were more likely to have a proximate upcoming life change, more likely to have been a recent victim of prejudice, and experienced proximate and chronic stress. The results identify behaviors and traits that security agencies can utilize to monitor and prevent lone-actor terrorism events. The correlated behaviors provide an image of how risk can crystalize within the individual offender and that our understanding of lone-actor terrorism should be multivariate in nature. Keywords: terrorism, terrorist, mental health, lone actor, behavior Attempts to understand the motivation and drives of the indi- Army (IRA), Northern Ireland loyalists, Hezbollah, German vidual terrorist have gone through many cycles. Through the 1970s terrorists, the National Liberation Front (FLN), Basque Home- studies emphasized pathological explanations that posited the land and Liberty (ETA), Colombian terrorists, global jihadists, compulsion to join a terrorist group, or the vulnerability to recruit- and captured Palestinian terrorists has provided evidence that ment, is inherent in those engaged in militancy. To this end, group-based terrorists are psychologically quite normal (Cren- researchers postulated deviant characteristics of the terrorist per- shaw, 1981; Ferguson, Burgess, & Hollywood, 2008; Heskin, sonality. Through the 1980s, psychoanalytical approaches con- 1984; Merari, 1998; Post, Sprinzak, & Denny, 2003; Rasch, cluded that terrorists were not the aggressive psychopaths por- 1979; Reinares, 2007; Sageman, 2005). Typically the popula- trayed to the public, but are hesitant, emotionally damaged youths tion of recruits does not tend to be psychopathological, or for who are victims of parental rejection that delayed their achieve- that matter highly uneducated and impoverished because of a ment of adult identity (Victoroff, 2005). Studies that emerged selection effect. Organizational elites seek to recruit those most through the late 1990s and early 2000s dismissed these approaches capable of undertaking assigned tasks. Most tasks require an on methodological and empirical grounds (Borum, 2004; Horgan, element of secrecy, calibrated violence, and technological 2005; Victoroff, 2005). know-how. Educated, psychologically healthy, and normal vol- A consensus soon emerged that group dynamics were key to unteers tend to be preferred for this particular reason. It was understanding terrorist motivation. For example, one academic, argued that those who seek to join but display signs of mental who in the past championed psychoanalytical interpretations of illness may be weeded out in the selection process (Silke, terrorist motivation, argued that “a clear consensus exists that it 2003). is not individual psychology, but group, organizational and The role of mental illness and personality became so com- social psychology, that provides the greatest analytical power in pletely downplayed that one noted expert recently stated: “we understanding this complex phenomenon” (Post, 2005,p.7). also tried to distinguish terrorists from violent lunatics. Crazies, This consensus was largely shaped through improved data by definition, could not be terrorists” (Jenkins, 2013, p. 9). In collection and primary interviews that refuted the above diag- other words, an act of targeted violence is either the action of a noses. For example, research carried out on the Irish Republican rational terrorist or an irrational mentally unstable civilian. Over the space of 40 years of research on terrorist motivation the literature has jumped from one extreme position (“they are all mentally ill”) to the exact opposite (“by definition, a terrorist This article was published Online First August 18, 2014. cannot be mentally ill”). This is also reflected in some major Emily Corner and Paul Gill, Department of Security and Crime Science, criminological research. For example, Gottfredson and Hirs- University College London. chi’s control theory views “regular criminals” as impulsive, Correspondence concerning this article should be addressed to Paul Gill, whereas terrorists need higher levels of control and are implic- Department of Security and Crime Science, University College London, 35 itly more calculating and, therefore, less likely to be mentally Tavistock Square, London, WC1H 9EZ, United Kingdom. E-mail: paul.gill@ucl.ac.uk ill. In reality, such distinctions are probably less clear-cut. A This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. CORNER AND GILL false dichotomy may exist that categorizes violent individuals article explores whether many of these counterintuitive findings as either a rational terrorist or an irrational and unstable indi- are related to the relatively large preponderance of individuals with vidual. mental illness diagnoses. Specifically we test a series of hypoth- This false dichotomy may be driven by two factors—a misun- eses related to selection effects, rationality, and stressors. derstanding of rationality and the focus on group-based actors. Some studies have shown that individuals with mental illness can Mental Illness and Selection Effects display rational motivations. For example, Gill, Horgan, and Deck- ert (2014) illustrate that lone-actor terrorists diagnosed with mental A number of studies compare lone and group offenders across a illness frequently display rational motives. Similarly, Borum wide range of crimes. The results regarding mental illness are (2013) highlights a number of terrorists with mental illness who mixed. For example, Coid et al. (2013) concluded that gang were capable of sophisticated attack planning. In an operational members demonstrate higher levels of psychiatric morbidity than study of assassins, attackers and near-lethal approachers, Fein and lone offenders. On the other hand, Bijleveld and Hendriks’ (2003) Vossekuil (1999), highlight cases of mentally ill individuals plan- found lone rapists to be significantly more likely to have problem- ning and executing behaviors as effectively as those lacking diag- atic personality structures than group rapists. Hickle and Roe- nosis. Sepowitz (2010) found lone juvenile arsonists more often came The few existing empirical studies of lone-actor terrorism sug- from unstable homes, and experienced school difficulties, behav- gest there is a greater preponderance of mental illness within this ioral problems, negative emotions, and expressed suicidal thoughts category of terrorist actor than that expected within a group-based more regularly. Hauffe and Porter (2009) suggest differing path- sample. Fein and Vossekuil (1999) found 61% of lone assassins ological processes at play between lone and group offenders. had previous contact with mental health services. Hewitt (2003) In terms of terrorism-specific studies Gruenewald et al. (2013) found 22% of American “loners” psychologically disturbed. Gill et compared far-right group and lone offenders, finding mental ill- al. (2014) found 31% of a sample of lone-actor terrorists to have ness prevalence differed across offender types (group offender, a history of mental illness. In perhaps the methodologically most 7.6%, and lone offender, 40.4%). Similarly, Hewitt (2003) de- sophisticated study, Gruenewald, Chermak, and Freilich (2013), scribes differences in prevalence of mental illness across terrorist compared a sample of lone extreme right-wing offenders with a group and lone actors (8.1% compared with 22%). These results sample of group-based extreme right-wing offenders. Lone- suggest psychopathological causation differs across terrorist type. offenders had a significantly higher rate of mental illness than This higher preponderance among lone-actor samples may be group-offenders (40% vs. 7.6%). because of processes that the group-based terrorism literature has These findings suggest a need for revisiting the issue of mental long hypothesized. Individuals displaying these traits will not be illness as a part of the process for some people becoming involved selected for recruitment. For example, Bueno de Mesquita (2005) in terrorism. Mental illness mechanisms remain systematically utilizes a game theoretic model to demonstrate differences be- unexamined, and there may be grounds to pursue a more concrete tween recruits and sympathisers to terrorist causes. The rationale understanding of how mental illness and psychological processes being that organizations screen recruits to select the most compe- influence an individual’s participation in and trajectory through tent to become cadres. Similarly, Horgan (2005) notes that partic- terrorist behaviors (Gill & Corner, 2013). The wider criminology ular individuals may never meet recruitment criteria because of literature suggests that much promise exists in utilizing mental overt psychological characteristics rendering them unsuitable. illness as a central variable with relation to criminogenic factors. Spaaij (2010) explains that because of psychological conditions, As Anderson (1997) explains, the symbiotic relationship between certain individuals fail to become recruited despite demonstrating mental illness and criminal behavior is complex. Comorbidity of willingness, and act independently instead. mental illness with other behaviors is well documented across the Hypothesis 1: Lone-actor terrorists will demonstrate a higher literature and include substance abuse (Todd et al., 2004) and prevalence of mental illness than group-based terrorist actors. violent and criminal convictions (Anderson, 1997). Utilizing a unique dataset of 119 lone-actor terrorists and a Following the above discussion, we may expect that lone-actor matched sample of group-based terrorists we first replicate the terrorists have previously tried to join a group. Given the temporal Gruenewald et al. (2013) study and test whether the significant and dynamic nature of mental illness, we may also expect that differences in mental illness also hold true across a sample of participating group members who later display these traits will be actors that contains ideological motivations other than far-right ejected from the group. It is consequently hypothesized: extremism. We then partition our lone-actor sample into two categories (those with and without mental illness diagnoses) and Hypothesis 2: There will be a difference between mentally ill test whether there are distinct characteristic, behavioral, or comor- and nonmentally ill lone actors concerning group entry, par- bidity differences between them. Finally, instead of treating mental ticipation and removal. illness diagnosis as a dichotomy (either you are mentally ill or not), we stratify our sample across a range of diagnoses and again test The above hypotheses presuppose that attitudinal affinity to a whether there significant differences appear. cause leads individuals to seek recruitment into a group of coideo- logues. Social movement theorists, however, argue that structural availability is holds greater explanatory power than attitudinal Theory affinity. In other words, predisposition to join a terrorist group is Most empirical studies of lone-actor terrorism are largely de- of little use if the would-be-terrorist does not possess the structural scriptive, and highlight a number of counterintuitive findings. This opportunities to join. Social movement research illustrates the This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. A FALSE DICHOTOMY? crucial role of structural and network factors in addition to indi- subject investigated was leading an exemplary life, defined by vidual attitudinal factors in motivating one toward activism (Mc- success in work and family. For almost all of the subjects their Adam, 1986). Looking at existing research on lone actor terrorists attack occurred after a downward spiral. For numerous subjects, and other analogous offender types, a common finding is that a one or several stressors appeared to trigger the process that led to large proportion of these samples are socially isolated individuals the assassination behavior. McCauley et al. (2013) compared who, therefore, may not have the interpersonal connections with a school attackers and assassins, finding evidence of stressors in potential recruiter. For example, the Gill et al. (2014) study of both cohorts (98% and “nearly half,” respectively). lone-actor terrorists characterized 52.9% of the sample as socially Agnew’s (2010) general strain theory of terrorism infers those isolated. Meloy, Hempel, Mohandie, Shiva, and Gray (2001) de- who act within a group experience collective strains (stressors) scribe 70% of their subset of adolescent mass murderers as loners seen as undeserved, caused by those with greater perceived power and outcasts among peers. Among Fein and Vossekuil’s (1999) and great in magnitude. Such stressors provoke action. However, cohort of assassins, “most” were illustrated as social isolates. Agnew concedes group involvement also aids alleviation of such Bijeveld and Hendriks (2003) investigation of sex offenders con- stressors. Group membership provides outlets for rage and discon- cluded that solo offenders (compared with group) score signifi- tent brought forth by strains, inadvertently lessening their adverse cantly lower on sociability. When we also consider that other effects. Lone actors do not possess the support structure to reduce studies have found a link between social isolation and mental these stressors, and the above evidence provides explanation for illness (Elisha, Castle, & Hocking, 2006; Thoits, 1983), we hy- the conclusions of Gill et al. (2014); Gruenewald et al. (2013), and pothesize that: Hewitt (2003). However, not all lone actors have a history of mental illness, so Hypothesis 3: Mentally ill lone actors are more likely to be it is necessary to determine if differences in experience of stressors characterized as socially isolated than those who are nonmen- across actors exist. Despite abundant statistical evidence concern- tally ill. ing stressors among both mentally ill and nonmentally ill perpe- trators of violence shown above; it is yet to be whether those with mental illness are more likely to encounter stressors and react to Stressors them than those who are nonmentally ill. Given the findings Farrington (1986) presents a general stress model; which hy- related to high-volume crimes, we hypothesize: pothesizes that stress is dependent upon the discrepancy between Hypothesis 4: Lone actors with a history of mental illness are the requirement posed by the stressor stimulus and the coping more likely to have encountered stressors than those with no behaviors utilized from the individual’s response capacities. Much recorded mental illness. of the criminology literature reports that the mentally ill are more susceptible to negative reactions to stressors. For example, Kend- ler, Karkowski, and Prescott (1999) investigated the impact of Irrationality and Violence stressors on the onset of major depression, concluding there to be a significant causal relationship, and noting individuals predis- As mentioned previously, recent research demonstrates that the posed to major depression place themselves into high-risk envi- supposed irrationality experienced by the mentally ill is not as ronments. Roberts, McLaughlin, Conron, and Koenen (2011) cite debilitating as previously thought (Borum et al., 2012; Gill et al., McLaughlin et al. (2010) who concluded that stress sensitization 2014; Fein & Vossekuil, 1999). Borum (2013) elucidates: “If the increases the likelihood of mental illness following exposure to subject... been given some diagnostic label, then there is a traumatic stressors. Borum et al. (2012) also note that symptoms of common tendency to regard that label as a master explanation of mental illness are sometimes not evident, except under continued the subject’s thinking, motives and behavior. It is not.” These stress. Situational explanations of crime contend that although assertions, however, are largely based on descriptive statistics or longer-term risk factors (in this case stress sensitization) may illustrative case studies and remain statistically untested. cause higher predisposition to engage in criminal and violent Furthermore, there is little understanding as to whether these behaviors, it is the shorter term risk factors (proximate stressors) types of actors differ in their ability to successfully carry out a that act as precursors to the actual commission of the crime. Gill violent attack. The study of the linkages between mental illness et al.’s (2014) work on lone-actor terrorism supports this. They and violence has a long history (Teplin, 1984). The Diagnostic and argue that although it is important to consider distal risk factors, Statistical Manual of Mental Disorders-Fourth Edition-Text Revi- shorter term risk factors are more operationally significant. Of the sion (DSM–IV–TR)(American Psychiatric Association, 2000) ex- 32.8% of lone actors who were impacted by stressors in their plains that across psychiatric disorders the risk of violence in- sample, 74.3% experienced those 12 months preceding the attack. creases comparable to that of the general population. Ouzir (2013) This process has also been highlighted in a number of analogous argues that impulsivity (that is associated with many mental ill- studies. Meloy et al. (2004) found 59% of their adolescent mass nesses) and reactive violence largely explain this increased risk of murderer sample experienced a “trigger” event hours or days violence. On the other hand, Hiday (1995) and Scott and Resnick before the murders. Hickle and Roe-Sepowitz’s (2010) research on (2006) argue those who are mentally ill to be no more dangerous juvenile arsonists found executors were more likely to “be in than the general population. These issues have also not been crisis,” having suffered a major stressor such as the death of a applied in a systematic sense to the types of violence associated parent, incidence of abuse, pregnancy, or suicide attempt. In 12 of with terrorist activity apart from James et al. (2007), who found Fein and Vossekuil’s (1999) 20 case studies, multiple stressors in that mentally ill perpetrators of attacks on European politicians the individual’s recent lives were present. They concluded that no engaged in higher levels of violence. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. CORNER AND GILL Hypothesis 5: Lone actors with a history of mental illness are convicted or died in the commission of their offense in the United no more likely to display irrational attack planning behaviors States and Europe since 1990. The sample includes violent and than those with no diagnosis. nonviolent behaviors carried out by individuals and isolated dyads who either self-radicalized, or radicalized via a larger organization Hypothesis 6: Lone actors with a history of mental illness are and then carried out acts external to command and control links. more violent than those with no diagnosis. Profiles were built using the LexisNexis archive of open source information, scholarly articles, and public record depositories, and Mental Illness Across a Spectrum the codebook includes 185 variables concerning sociodemographi- To expand the terrorist literature it is necessary to expand the cal information, antecedent, event and postevent specific behav- dichotomous thinking an individual is either mentally ill or not. iors. Different disorders display different symptoms (DSM–IV–TR, To compare group and lone actors, we also created a sample of American Psychiatric Association, 2000; International Statistical group terrorist actors. The observations were sourced from Sim- Classification of Diseases and Related Health Problems-10th re- cox, Stuart, Ahmed, Murray, and Carlile (2011) and Mother Jones vision (ICD-10), World Health Organization, 2010). By viewing (2013), which contain open source profiles on U.S. and non-U.S. actions displayed by a terrorist as either mentally ill or not, the terror-based activities since September 11, 2001. A systematic literature becomes stagnant and prevention methods are not as stratified sampling methodology was utilized to gather the sample effective as possible. Psychiatric literature often focuses upon of 119 group terrorist actors. The data were matched to the lone levels of violence, demonstrated by numerous studies. Antisocial actor sample through the country of attack variable (55 U.S. and 64 personality disorder is associated with violence (DSM–IV–TR, non-U.S.). This variable was selected to reflect differing psychi- American Psychiatric Association, 2000). Fazel and Danesh atric practices with concerns to law enforcement (James et al., (2002) describe how this disorder is often seen in prison settings. 2007). Group actors were chosen based on confirmed affiliations In a review of 13 investigations concerning violence in mentally ill with organizations, and incarceration not including deportation. subjects, Schizophrenia was concluded as being the most reliable Once outliers were excluded there was a sample of 142 non-U.S. indicator, followed by personality disorders and those with organic group actors and a sample of 286 U.S. group actors. Each actor brain trauma. (Krakowski, Volavka, & Brizer, 1986). Shaw et al. was assigned a random number (generated using RAND func- (2006) provide evidence for differing prevalence rates of mental tion in Excel) and using a systematic method (k p/n); in this illnesses across individuals convicted of homicide. Swanson, Hol- instance k observation, p population, and n sample size. zer, Ganju, and Jono (1990) concluded different disorders present Sampling intervals were generated (2.22 for actions non-U.S. different levels of violence, ranging from phobias (lowest) to drug countries and 5.2 for U.S.) and a sample containing 55 U.S. actors dependence (highest). This investigation aims to determine if, and 64 non-U.S. actors was produced (SMART, 2012, p. 9). Using alongside violence, other variables previously discussed differ the same extensive search tools as the Gill et al. (2014) study, we across disorders. Therefore, the hypothesis formulated is: coded variables related to mental health issues for each of the chosen group-based actors. Hypothesis 7: There will be differences in variables across Gill et al.’s (2014) codebook examined mental illness as a disorders in the cohort. dichotomous variable. We created additional variables including the number and name of diagnoses and diagnostic categories. It is also important to consider comorbidity across psychiatric These variables were developed after extensive examination of the diagnoses. Saxe et al. (1993) found patients who met criteria for available literature on each actor. Available literature was sourced dissociative disorder were significantly more likely to suffer from from the Lexis Nexus database, sworn affidavits, indictments, major depression, PTSD, substance abuse, and borderline person- manifestos, warrants, trail proceeding transcripts, trial memoran- ality disorder. Kessler, Chiu, Demler, and Walters (2005) explain; dums, government and expert witness reports, and competency comorbidity of disorders is not as common as being diagnosed evaluations. The diagnosis name was located in the literature, and with one disorder, but the most severe and pervasive cases are reliability and quality of the source was taken into account. For concentrated in the highly comorbid. Singleton et al. (1998) found example, one actor was coded as suffering from Asperger’s and 76% of those with a mental illness in the prison population to be depression (cited in trial proceedings); however, a newspaper diagnosed with two or more disorders. In a more recent epidemi- article citing a “friend” (neighbor) as saying they suffered from ological survey, Elbogen and Johnson (2009) concluded comor- schizophrenia was discounted, as there was no further evidence for bidity of disorders to be a reliable predictor of violence incidence. this in any of the other sources concerning said actor. To ascertain Abram and Teplin (1991) suggest this pattern is because the the number of diagnoses the same process was carried out. Diag- complex needs of those with multiple diagnoses make them diffi- nostic categories were noted either from a confirmed diagnosis in cult to place in treatment facilities, and they are arrested as a form articles, or from a series of symptoms that were cross-referenced of disorder management. Taking into account this evidence it is with diagnostic material, and given a provisional diagnosis (ICD- hypothesized: 10, World Health Organization, 2010). For those actors where Hypothesis 8: There will be differences in variables across specific diagnoses were not available and no symptoms provided comorbid disorders in the cohort. (e.g., the literature on one actor gave no confirmed diagnoses but confirmed that a mandatory treatment order was given) the out- Data and Method comes were recorded and it was recorded the actor to have one The sample includes an extensive codebook from Gill et al.’s diagnosis and a diagnostic code of 11 (nonspecific). The ICD-10 (2014) dataset of 119 lone-actor terrorists. Actors were either diagnostic categories are displayed in Table 1, and is utilized This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. A FALSE DICHOTOMY? Table 1 actors with mental illness, D(119) 0.54, p .001 to be signif- ICD-10 Diagnostic Categories icantly non-normal. Levene’s test demonstrated that for mental illness, variances were significantly different between lone and Diagnostic category Diagnoses or disorders group actors, F(1, 236) 284.804, p .001. Because the data violated assumptions and are binary categorical, a test was F00-F09 Organic F10-F19 Substance use completed and odds ratio calculated. A test demonstrated a F20-F29 Schizophrenia, schizotypal, and delusional significant association between offender type (group or lone) and F30-F39 Mood 2 mental illness, (1) 33.422, p .001. Based on the odds ratio, F40-F48 Neurotic, stress related, and somatoform the odds of a lone actor having a mental illness is 13.49 (95% F50-F59 Behavioral syndromes associated with confidence interval [CI]: 4.630, 40) times higher than the odds of physiological and physical factors F60-F69 Personality a group actor having a mental illness. F70-F79 Intellectual disabilities (“mental retardation”) To compare lone actors with and without a history of mental F80-F89 Disorders of psychological development illness, we followed the procedures of Gruenewald et al. (2013). F90-F98 Behavioral and emotional, onset in childhood, We first conducted a series of bivariate tests such as analyses and adolescence F99-F99 Unspecified and, where appropriate, Fisher’s exact tests. Table 2 outlines the significant differences between these subsets. Variables displaying significant differences were then input into a binary logistic re- gression to determine the strength of their predictive value in terms because of its widespread usage, and is a more valid measure for of predicting whether the observation had a history of mental prevention implications. illness or not. To determine whether variables have any predictive strength when considering differing and multiple diagnoses, the Results significant variables from the binary logistic regression were uti- Hypothesis 1: Lone-actor terrorists will demonstrate a higher lized in a multinomial regression. prevalence of mental illness than group-based terrorist actors. Hypothesis 2: There will be a difference between mentally ill We first tested whether the rates of mental illness were higher and nonmentally ill lone actors concerning group entry, par- among our sample of lone actors compared with our group-based ticipation and removal. sample. Whereas the rate of mental illness among the lone-actor sample was 31.9%, the corresponding figure for the group-actor sample was For Hypothesis 2, we compared our lone-actor subsamples 3.4%. Kolmogorov-Smirnov calculated the percentage of lone across behavioral variables including whether (a) the individual’s actors with mental illness, D(119) 0.43, p .001 and group spouse was part of a wider movement, (b) individual received Table 2 Observed Percentages for Nonmentally Ill and Mentally Ill Actors Mentally ill Nonmentally ill Hypothesis 2 1.2% Individual’s spouse or partner part of wider movement. 18.4% Command and control links with others. 7.9% 21.0% Hypothesis 4 Individual’s parents divorced. 31.6% 9.9% Proximate upcoming life change. 15.8% 6.2% In build up to event; individual experienced being target of prejudice. 28.9% 11.1% In build up to event; individual experienced being disrespected. 28.9% 14.8% Individual recently under elevated level of stress. 44.7% 27.2% Chronic stress in individual’s life. 34.2% 19.8% Hypothesis 5 Recent increase in levels of physical activity. 21.1% 8.6% Individual had stockpile of weapons. 63.2% 40.7% Individual expressed desire to hurt others. 76.3% 58.0% Discriminate or nondiscriminate target? 73.7% 50.6% Individual claimed responsibility publicly. 53.3% 38.3% Hypothesis 6 Individual engaged in violent behavior previous to terrorist event. 52.6 30.9% Violent attack carried out? 65.8% 44.4% Did the individual kill? 55.3% 24.7% Did the individual injure? 52.6% 25.9% Additional variables Single issue inspired individual. 28.9% 12.3% Born in United States. 63.2% 39.5% Held a Ph.D. 10.5% 2.5% p .1. p .05. p .01. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. CORNER AND GILL some form of hands on training from a group, (c) the individual’s individuals who experience chronic stress are 2.13 (95% CI: 0.889, family or close associates were involved in politically violent 5.018) times more likely to have a mental illness, (1) 2.933, groups, (d) the individual interacted face-to-face with members of p .1. a wider network, (e) the individual received help in procuring Hypothesis 5: Lone actors with a history of mental illness are weaponry for the attack, (f) there was evidence of some form of no more likely to display irrational attack planning behaviors command and control, (g) the individual tried to recruit others, and than those with no diagnosis. (h) the individual was ever rejected or ejected from a wider network or group. Some significant associations were found be- Hypothesis 6: Lone actors with a history of mental illness are tween mental illness and group participation. Those who had a more violent than those with no diagnosis. spouse or partner who was involved in a wider movement were 18.07 (95% CI: 2.134, 152.914) times more likely to be mentally To test issues concerning rationality, we focused on variables ill (Fisher’s test; p .001). Those with command and control links related to attack planning, attack commission, and postattack be- with others were less likely (OR 0.32, 95% CI: 0.880, 1.178) to haviors. These included noting whether the individual (a) became have a mental illness, obsessed or fixated with a specific event or phenomena in the (1) 3.171, p .1. All other variables attack’s build-up, (b) expressed a desire to hurt others, (c) make related to this hypothesis presented nonsignificant results. verbal statements about their intent/beliefs to friends/family/wider Hypothesis 3: Mentally ill lone actors are more likely to be audiences, (d) have others aware of their grievance or extremist characterized as socially isolated than those who are nonmen- ideology, (e) have a history of violence before this terrorist inci- tally ill. dent, (f) consumed propaganda of a wider movement or other lone-actor, (g) sought legitimization from epistemic authority fig- For this hypothesis, we tested a range of behaviors including ures for his or her actions, (h) increased levels of physical activity whether the individual was (a) in a relationship, (b) unemployed, in the build-up to the event, (i) engaged in dry-runs, (j) stockpiled (c) living alone at the time of the event, and (d) characterized as weapons, (k) successfully carried out an attack, (l) targeted dis- being socially isolated. No variables demonstrated significant as- criminately or indiscriminately, (m) used multiple attack methods, sociations. Of particular interest here is that the results indicate a (n) killed anybody, (o) injured anybody, or (p) provide a claim of lack of association between mental illness and social isolation, responsibility. (1) 0.002, p .963. The odds ratio (0.98, 95% CI: 0.454, Those with a history of violence are 2.49 (95% CI: 1.127, 5.497) 2.125) indicates the null hypothesis should be accepted, and pre- times more likely to have a mental illness, (1) 5.212, p .05. vious nonstatistical conclusions in the literature should be inter- Those who increase physical activity levels are 2.82 (95% CI: preted cautiously. 0.939, 8.465) times more likely have a mental illness (Fisher’s test; p .1). Those who stockpile weapons are 2.49 (95% CI: 1.127, Hypothesis 4: Lone actors with a history of mental illness are 5.518) times more likely to be diagnosed with a mental illness, more likely to have encountered stressors than those with no (1) 5.208, p .05. Individuals who express a desire to hurt recorded mental illness. others are 2.33 (95% CI: 0.978, 5.555) times more likely to have Here, we tested variables including whether the individual had a mental illness, (1) 3.750, p .1. Those whose target is (a) divorced parents, (b) previous military experience, (c) become discriminate are 2.73 (95% CI: 1.175, 6.348) times more likely to recently unemployed, (d) a history of substance abuse, (e) expe- be mentally ill, (1) 5.649, p .05. Actors who carry out a rienced a significant work-related stressor, (f) a proximate life goal violent attack are 2.4 (95% CI: 1.079, 5.354) times more likely to interrupted, (g) experienced being degraded or disrespected by have a mental illness, (1) 4.717, p .05. Individuals who kill others, (h) experienced being the target of an act of prejudice, (i) in an attack are 3.77 (95% CI: 1.668, 8.510) times more likely to experienced being the victim of physical or verbal assault, (j) be mentally ill, (1) 10.705, p .001. Actors who injure others recent personal relationship problem, (k) recent financial prob- in an attack are also 3.18 (95% CI: 1.415, 7.120) times more likely lems, (l) recently been under an elevated level of stress, (m) to have a mental illness, (1) 8.169, p .01. Individuals who experienced long-term sources of stress, and (n) about to experi- subsequently claim responsibility publicly are twice as likely (95% ence a proximate upcoming life change. CI: 0.913, 4.350) to be mentally ill, (1) 3.035, p .1. Some significant associations were found between mental ill- Finally, we tested a series of other variables to see whether ness and the experience of stressors. Those who have witnessed significant differences were apparent among the lone-actor terror- parental divorce are 4.21 (95% CI: 1.549, 11.452) times more ist subgroups. Those who operate within the United States, hold a likely to be diagnosed with a mental illness, Ph.D. and are motivated by single-issue causes are more likely to (1) 8.713, p have a history of mental illness. For obvious reasons, we decided .01. Several proximate stressors demonstrated significant associa- tions. Actors with a proximate upcoming life change are 2.85 (95% to keep these variables in the logistic regression below. Other CI: 0.811, 10.014) times more likely to have a mental illness variables such as criminal history showed no significant differ- (Fisher’s test; p .1). Those who experience prejudice are 3.26 ence. (95% CI: 1.216, 8.734) times more likely to have a mental illness, To determine the probability that mental illness occurs in an individual given a set of predictor variables, a binary logistic (1) 5.885, p .05, and those who experience disrespect are regression analysis was carried out. The logistic regression anal- 2.34 (95% CI: 0.923, 5.945) times more likely to have a mental illness, ysis showed that in combination, the independent variables signif- (1) 3.313, p .1. Individuals who experience current icantly impacted upon mental illness, stress are 2.17 (95% CI: 0.970, 4.858) times more likely to be (20) 60.667, p .001. diagnosed with a mental illness, (1) 3.627, p .1, and The model correctly predicted 83.2% of responses. A number of This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. A FALSE DICHOTOMY? individual variables were significant predictors of mental illness, category, (45) 110.530, p .001. Table 4 depicts an overview as shown in Table 3. Odds of greater than one indicate a positive of the results. relationship between the predictor and dependent variable. These results illustrate there to be certain variables that have a These results illustrate a variety of variables with odds ratios significant main effect on diagnostic category (more likely than suggestive of an impact on mental illness. These variables include those who do not perform a behavior). Following the odds ratios, having a spouse or partner involved in a wider movement (65.53 individuals with a spouse or partner involved in terror are 22.2 [95% CI: 3.726, 1149.388] times more likely to have a mental (95% CI; 0.704, 1000) times more likely to have a diagnosis of illness), making a public claim of responsibility (2.86 [95% CI: schizophrenia (F20 –29) and 250 (95% CI; 5.495, 13734.377) 0.590, 19.974] times more likely), injuring others in the attack times more likely to be diagnosed with a mood disorder (F30 –39). (14.27 [95% CI: 1.880, 108.207] times more likely) having pre- Individuals who injure in an attack are 11.63 (95% CI; 2.092, vious history of violence (3.21 [95% CI: 0.852, 12.070] times 66.600) times more likely like have schizophrenia and 41.6 (95% more likely), stockpiling weapons (3.97 [95% CI: 1.202, 13.130] CI; 2.488, 1000) times more likely to have a mood disorder. Those times more likely), witnessing parental divorce (6.02 [95% CI: who display prior violence are 5.15 (95% CI; 1.106, 24.390) times 1.221, 29.710] times more likely), experiencing an upcoming life more likely to be schizophrenic. Individuals witness to a parental change (7.04 [95% CI: 0.963, 51.445] times more likely), being a divorce are 9 (95% CI; 0.872, 90.900) times more likely to have a victim to an act of prejudice (4.37 [95% CI: 0.808, 23.593] times mood disorder and 40 (95% CI; 1.497, 1000) times more likely to more likely) and experiencing chronic stress (3.75 [0.935, 15.037] have a diagnosis in category F80 – 89 (developmental disorders). times more likely). Actors experiencing a proximate life change are 23.26 (95% CI; 2.841, 200) times more likely to be schizophrenic and 26.32 (95% Hypothesis 7: There will be differences in variables across CI; 0.838, 1000) times more likely to have a mood disorder. disorders in the cohort. Individuals who experience chronic stress are 4.2 (95% CI; 0.842, We ran a multinomial logistic regression to determine the prob- 20.833) times more likely to be diagnosed with schizophrenia and ability that different mental illnesses occur in individuals given a 8.06 (95% CI; 0.802, 83.333) times more likely to have a mood set of predictor variables (different manifestations of lone actor disorder. behavior). The included diagnostic categories contained a sample of at least three actors. The analysis showed that, in combination, Hypothesis 8: There will be differences in variables across the independent variables significantly impacted upon diagnostic comorbid disorders in the cohort. Table 3 Logistic Regression 95% CI for odds ratio Variable B (SE) Significant Lower Exp (B) Upper H2 3.736 65.526 1149.388 Individual’s spouse or partner part of wider movement. 4.182 (1.462) 0.004 Command and control links with others. 1.163 (1.218) 0.339 0.029 0.312 3.399 H4 Individual’s parents divorced. 1.795 (0.814) 0.027 1.221 6.022 29.710 Proximate upcoming life change. 1.952 (1.015) 0.054 0.963 7.040 51.445 In build up to event; individual experienced being target of prejudice. 1.474 (0.861) 0.087 0.808 4.366 23.593 In build up to event; individual experienced being disrespected. 0.160 (0.810) 0.843 0.240 1.174 5.742 Individual recently under elevated level of stress. 0.375 (0.747) 0.615 0.159 0.687 2.968 Chronic stress in individual’s life. 1.321 (0.709) 0.062 0.935 3.749 15.037 H5 Recent increase in levels of physical activity. 0.396 (0.934) 0.671 0.108 0.673 4.195 Individual had stockpile of weapons. 1.379 (0.610) 0.024 1.202 3.972 13.130 Individual expressed desire to hurt others. 0.198 (0.664) 0.766 0.223 0.821 3.018 Discriminate or nondiscriminate target? 0.343 (0.699) 0.623 0.358 1.410 5.545 Individual claimed responsibility publicly. 1.050 (0.619) 0.090 0.850 2.858 9.609 H6 Individual engaged in violent behavior previous to terrorist event. 1.165 (0.676) 0.085 0.852 3.207 12.070 Violent attack carried out? 0.916 (1.128) 0.417 0.044 0.400 3.653 Did the individual kill? 0.092 (0.845) 0.914 0.209 1.096 5.739 Did the individual injure? 2.658 (1.034) 0.010 1.880 14.265 108.207 Additional variables Single issue inspired individual. 1.234 (0.898) 0.170 0.590 3.434 19.974 Born in the United States. 0.346 (0.699) 0.621 0.359 1.413 5.563 Held a Ph.D. 1.591 (1.381) 0.249 0.328 4.911 73.526 Constant 5.267 (1.595) 0.001 0.005 Note.B regression coefficient; Exp (B) odds ratio. p .1. p .05. p .01. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. CORNER AND GILL To establish whether comorbidity of mental disorders affects aspects of terrorist behavior, we ran a multinomial logistic regres- sion. In combination the independent variables significantly im- pacted upon comorbid disorders, (27) 78.679, p .001. Table 5 denotes an overview of statistical findings. These results illustrate there to be certain variables that had a significant main effect on diagnostic category (more likely than those who do not perform the behavior). The odds ratios demon- strate those with a spouse involved in terror are 45.45 (95% CI; 3.984, 500) times more likely to have one diagnosis, 47.62 (95% CI; 1.221, 1000) times more likely to have two diagnoses and 500 (95% CI; 4.695, 57903.880) times more likely to have three or more diagnoses. Individuals who injure are 5.1 (95% CI; 1.520, 17.241) times more likely to have one diagnoses, 12.5 (95% CI; 1.314, 125) times more likely to have two diagnoses, and 50 (95% CI; 1.724, 1000) times more likely to have three or more diagno- ses. Individuals with a history of violence are 2.76 (95% CI; 0.861, 8.850) times more likely to have one diagnosis. Individuals who stockpile weapons are 3.65 (95% CI; 1.070, 12.500) times more likely to have one diagnosis, 16.67 (95% CI; 1.323, 200) times more likely to have two diagnoses, and 11.24 (95% CI; 0.693. 166.667) times more likely to have three or more diagnoses. Individuals witness to their parents’ divorce are 23.81 (95% CI; 2.825, 200) times more likely to have two diagnoses and 23.81 (95% CI; 1.669, 333.333) times more likely to have three or more diagnoses. Individuals who experienced prejudice were 4.95 (95% CI; 1.186, 20.833) times more likely to have one diagnosis. Indi- viduals experiencing chronic stress are 14.71 (95% CI; 1.403, 142.857) times more likely to have two diagnoses. Individuals who experience a proximate life change are 500 (95% CI; 5.435, 31191.516) times more likely to have three or more diagnoses. Discussion and Conclusions Together the results illustrate the need to readjust our under- standing of terrorism and mental illness in a number of ways. First, the results suggest there is a stronger association between mental illness and lone-actor terrorists than mental illness and group- based terrorists. This reflects the findings of Gruenewald et al.’s (2013) analysis of extreme right-wing offenders who have caused fatalities in the U.S. When we compared our lone actors with a history of mental illness to those without, we further found that those with a history were significantly less likely to have some form of command and control link. This further bolsters the argument that selection effects are at play. Future qualitative research may focus upon the strategies deployed by terrorist re- cruiters in selecting new cadre. It is also important here to recog- nize the potential for selectivity bias with regard to using open- source data (Chermak et al., 2010). There is the possibility that reporters are aware of the potential that lone actors are more likely mentally ill, investigate that avenue further and more rigorously and report their findings. As reported above, great care was taken to source information from outside of newspaper reports and we referred to hierarchy of credible sources in the case of conflicting reports. Future research may compare the rates of reporting of mental illness within group actors in cases during the 1970s and 1980s when the terrorist as mentally ill idea was salient to con- temporary cases to check whether such prevailing notions impact upon reporting procedures. This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Table 4 Multinomial Logistic Regression Diagnostic category Variable F20-29 F30-39 F40-48 F60-69 F80-89 2 2 Individual’s spouse or partner part of wider B 3.090, Wald (1) 3.099, B 5.616, Wald (1) 7.921, —— — movement. p .1, 95% CI [0.001, 1.420] p .01, 95% CI [0.000, 0.182] Individual claimed responsibility publicly. — — — — — 2 2 Did the individual injure? B 2.458, Wald (1) 7.852, B 3.719, Wald (1) 6.734, —— — p .01, 95% CI [0.015, 0.478] p .01, 95% CI [0.001, 0.402] Individual engaged in violent behavior B 1.642, Wald (1) 4.361, —— —— previous to terrorist event. p .05, 95% CI [0.041, 0.904] Individual had stockpile of weapons. — — — — — 2 2 Individual’s parents divorced. — B 2.198, Wald (1) 3.405, —— B 3.676, Wald (1) 4.845, p .1, 95% CI [0.011, 1.147] p .05, 95% CI [0.001, 0.668] 2 2 Proximate upcoming life change. B 3.144, Wald (1) 8.614, B 3.280, Wald (1) 3.459, —— p .01, 95% CI [0.005, 0.352] p .1, 95% CI [0.001, 1.193] In build up to event; individual experienced being target of prejudice. — — — — — 2 2 Chronic stress in individual’s life. B 1.434, Wald (1) 3.063, B 2.088, Wald (1) 3.143, —— — p .1, 95% CI [0.048, 1.188] p .1, 955 CI [0.012, 1.247] Note. Reference category no diagnosis; — not significant. A FALSE DICHOTOMY? Second, the significant association between mental illness and having a spouse or partner associated with a wider movement suggests those with mental illness may be susceptible to ideolog- ical influences in their immediate social environment. Additional case study-based research may identify similarities in ideological leanings and influence between couples. Third, the most common recurring theme in the literature con- cerning lone actors is social isolation. This work does not largely deviate from previous conclusions. It demonstrates 52.9% of lone actors to be socially isolated. This article attempted to bridge the link between the social isolation hypothesis (Thoits, 1983 citing Faris, 1934) and the socially isolative behaviors seen in lone actors. However, the resulting statistics demonstrate those with a history of mental illness are no more likely to have an association with social isolation than those without. This result provides im- portant implications for countering lone actor terrorism, and sug- gests community services hold the potential to be the most effec- tive discipline in combating this facet of behavior. Further work should investigate community awareness programs concerning identification of potential socially isolated lone actor offenders. Fourth, we found that lone actors with a history of mental illness are more likely associated with single-issue ideologies than al- Qaeda inspired or extreme right-wing ideologies. This may also help explain the (initially) counterintuitive finding that those with mental illness are significantly more likely to discriminate between potential targets. Fifth, those who hold a single-issue ideology are more typically fixated upon a target that they see as wholly responsible for their grievance. For example, Walter Leroy Moody Jr. mailed pipe bombs to specific targets affiliated with criminal courts and Scott Roeder targeted an abortion provider he extensively wrote about online. These behaviors are reflected in certain mental illnesses. Those with mental illness can experience intrusive thought pro- cesses, neuroticism and psychotic episodes (American Psychiatric Association, 2000; Link & Stueve, 1994; World Health Organiza- tion, 2010) that cause fixations upon specific “targets” who the individual view as responsible. This finding also follows Clarke and Newman’s (2006) work on situational crime prevention. They hypothesize successful attacks to be more likely when opportuni- ties are apparent. Individuals fixating upon singular targets will encounter a great range of opportunities. The above evidence also counters the school of thought which explains irrationality to negatively affect behavior of individuals (Hiday & Burns, 2010,p. 479), impairing their capability of striking. To provide further statistical evidence, future investigations also ought to consider empirically investigating the targets of attacks. The significant finding that those with a mental illness have an association with claiming responsibility publicly also fits diagnostic criteria of certain mental illnesses (grandiosity, extraversion, delusions, de- lirium, impulsivity, and attention seeking behaviors; American Psychiatric Association, 2000; World Health Organization, 2010). The finding that those with a mental illness have an association with expressing a desire to hurt others may provide useful direc- tions for prevention efforts. To provide further statistical evidence, it is advised that future investigation should consider diagnostic criteria and links with irrational behaviors demonstrated by men- tally ill lone actors. Sixth, despite previous research showing definitive associations between individual’s with mental illness and crime (Anderson, This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. Table 5 Multinomial Regression Number of diagnoses Variable 12 3 2 2 2 Individual’s spouse or partner part of wider movement. B 3.825, Wald (1)9.432, B 3.873, Wald (1) 4.271, B 6.256, Wald (1) 6.776, p .01, 95% CI [0.002, 0.251] p .05, 95% CI [0.001, 0.819] p .01, 95% CI [0.000, 0.213] Individual claimed responsibility publicly. — — — 2 2 2 Did the individual injure? B 1.630, Wald (1) 6.960, B 2.523, Wald (1) 4.833, B 3.899, Wald (1) 5.193, p .01, 95% CI [0.058, 0.658] p .05, 95% CI [0.008, 0.761] p .05, 95% CI [0.001, 0.580] Individual engaged in violent behavior previous to terrorist event. B 1.016, Wald (1) 2.922, —— p .1, 95% CI [0.133, 1.161] 2 2 2 Individual had stockpile of weapons. B 1.295, Wald (1) 4.273, B 2.818, Wald (1) 4.737, B 2.414, Wald (1) 2.894, p .05, 95% CI [0.080, 0.935] p .05, 95% CI [0.005, 0.756] p .1, 95% CI [0.006, 1.444] 2 2 Individual’s parents divorced — B 3.169, Wald (1) 8.489, B 3.159, Wald (1) 5.474, p .01, 95% CI [0.005, 0.354] p .05, 95% CI [0.003, 0.599] Proximate upcoming life change. — — B 6.020, Wald (1) 7.433, p .01, 95% CI [0.000, 0.184] In build up to event; individual experienced being target of prejudice. B 1.599, Wald (1) 4.813, —— p .05, 95% CI [0.048, 0.843] Chronic stress in individual’s life. — B 2.685, Wald (1) 5.029, — p .05, 95% CI [0.007, 0.713] Note. Reference category no diagnosis; — not significant. CORNER AND GILL 1997; Holcom & Ahr, 1988; Singleton et al., 1998; Teplin, 1984), Tenth, the significant variables in the multinomial regression there were no significant associations found between mental ill- concerning comorbidity of disorders do not present a strong case ness and prior criminal behavior. Those with a history of mental for rejecting the null hypothesis. Most significant variables were illness are no more likely to have a criminal history that those with found to be so across all categories. Individual’s with one diag- no history. However, because of the type of data analyzed, it was nosis were, however, more likely to be violent before the event, not possible to discern dates for previous criminal convictions and contradicting previous evidence (Swanson et al., 1990). The pre- vious multinomial regression also demonstrated Schizophrenic any psychiatric diagnoses. This could have helped determine individuals to display the same behavior. In the current cohort it is whether the terrorist act immediately followed the onset of a possible those diagnosed with Schizophrenia had no comorbid disorder. Further investigations should complete such analyses, to diagnoses, resulting in the above finding. Individuals with dual- definitively conclude whether those with a mental illness are diagnoses were significantly connected to chronic stress. This statistically more likely to possess criminal convictions. Although finding reflects the previous multinomial regression. Those with those with a history of mental illness are not more likely to have mood disorders were also significantly more likely to experience a prior criminal conviction, the cohort did have a strong statistical this variable, and of those with a mood disorder in this cohort 66% link with prior violent behaviors. These results support the pre- had comorbid diagnoses, which may have skewed resulting sig- ceding literature that those with a mental illness are more likely to nificant values. The significant finding that those with three or be violent. It is suggested that future investigations should consider more disorders were more likely to have a proximate upcoming an actor’s history of violence and examine what constitutes violent life change should be investigated further, because of its potential behavior and its link to criminal convictions. function for prevention policies. The cohort size of this regression Seventh, the statistical analyses demonstrated significant asso- has limited the significant findings. It is also a preliminary test. ciations between mental illness and stressors. The stressor that Further investigation should expand upon comorbidity and partic- remained most highly significant across both bivariate and multi- ularly different combinations of comorbid disorders to identify any variate tests was if the individual’s parents were divorced. It is also behaviors useful for mental health professionals. Because mental possible to view divorce as a control variable and a proxy for disorders often share symptoms, further research may also focus social integration or lower levels of individual attachment and upon analyzing symptoms of mental illness rather than the diag- involvement. On a similar note, studies of far-right fatal violence noses themselves (Douglas, Guy, & Hart, 2009). Unfortunately, in the U.S. show that these offenders are more likely to live in this was not possible in this article because of constraints in the counties with higher divorce rates at the time of their offense. To available data. However, both authors are currently working along- expand on this investigation, further research should test the time- side colleagues with the United Kingdom’s North West Counter scale of stressor variables and the impact upon mental illness Terrorism Unit under Project Regulus to consider both differential onset. Only a small proportion of all stressor variables analyzed diagnosis and symptoms as risk factors of violence in a sample of showed a significant association with mental illness, aiding pro- lone domestic extremists. fessionals when examining patients, as it provides direction for Finally, the findings of this investigation provide evidence those possible intervention. lone actors with a history of mental illness are also more likely to Eighth, 45% of the significant variables identified in the bivari- engage in certain antecedent events and behaviors that security and ate analyses were also significant in the logistic regression analy- policing agencies can utilize to monitor and prevent further devel- ses. These variables provide direction for mental health profes- opments in attack plotting. In essence, the correlated behaviors sionals, as they should consider liaising with security professionals provide an image of how risk can crystalize within the individual concerning patients displaying such variables. offender and that our understanding of lone-actor terrorism should Ninth, the first multinomial regression analysis demonstrated be multivariate in nature. The findings presented in this article certain variables significantly impact upon certain mental illness support James et al. (2007) and Chermak, Freilich, and Simone diagnoses (despite the low number of individuals in each cate- (2010), who emphasize the need for cooperation between agencies gory). Schizophrenia and associated disorders is the only diagnos- and widespread sharing of information. The empirical evidence tic group to be significantly associated with previous violence and suggests mental health professionals may have a role in preventing this supports past research (Krakowski et al., 1986; Shaw et al., lone-actor terrorist attacks. If mental health professionals were 2006). Mood disorders demonstrate their susceptibility to stres- aware of these findings then screening processes can be carried out sors. Those who had divorced parents were significantly more by security agencies on patients that present similar antecedents likely to have psychological development disorders (in this cohort, and behaviors in medical evaluations. Examples of multidisci- autism). This reflect the stress of raising a child with such a plinary cohesion concerning criminal offenses include the Multi- disorder (Higgins, Bailey, & Pearce, 2005). Negative statistics Agency Public Protection Arrangements (MAPPA) and the Fix- (though not significant) were found concerning stress related dis- ated Threat Assessment Centre (FTAC). MAPPA involves orders and violent behavior (supporting Swanson et al., 1990). multiple agencies (including mental health professionals, proba- Negative associations were also found between personality disor- tion service, police forces, and the HM prison service) who are ders and autism and having a spouse or partner related to a terror tasked with managing offenders, and focuses upon a range of movement, which may be indicative of not having a spouse be- offenders (Ministry of Justice, 2012). FTAC is an initiative aiming cause of the detrimental nature of these disorders. These results to protect politicians, the British Royal Family, and other public support previous research. Future work may investigate a larger figures from fixated individuals, by incorporating input from the cohort of diagnoses listed by the ICD-10 to confirm and expand department of health and the metropolitan police (Fixated Re- upon these findings. search Group, 2013). MAPPA focuses upon offenders after con- This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. A FALSE DICHOTOMY? viction and release, whereas FTAC assesses potential threats and proachers. Journal of Forensic Sciences, 44, 321–333. Retrieved from http://www.secretservice.gov/ntac/ntac_jfs.pdf aims to provide psychiatric services to offenders as a prevention Ferguson, N., Burgess, M., & Hollywood, I. (2008). Crossing the Rubicon: mechanism. We argue that data-driven analyses such as this article Deciding to become a paramilitary in Northern Ireland. International can help provide an empirical knowledge base from which orga- Journal of Conflict and Violence, 2, 130 –137. http://ijcv.org/index.php/ nizations like FTAC and MAPPA can make more informed deci- ijcv/article/viewArticle/31 sions concerning risk and capability. Fixated Research Group. (2013). Preventing harm and facilitating care. Retrieved from http://www.fixatedthreat.com/ References Gill, P., & Corner, E. (2013). Disaggregating terrorist offenders: Implica- tions for research and practice. Criminology & Public Policy, 12, 93– Abram, K. M., & Teplin, L. A. (1991). Co-occurring disorders among 101. doi:10.1111/1745-9133.12015 mentally ill jail detainees: Implications for public policy. American Gill, P., Horgan, J., & Deckert, P. (2014). Bombing alone: Tracing the Psychologist, 46, 1036 –1045. doi:10.1037//0003-066X.46.10.1036 motivations and antecedent behaviors of lone-actor terrorists. Journal of Agnew, R. (2010). A general strain theory of terrorism. Theoretical Crim- Forensic Sciences, 59, 425– 435. doi:10.1111/1556-4029.12312 inology, 14, 131–153. Gruenewald, J., Chermak, S., & Freilich, J. D. (2013). Distinguishing American Psychiatric Association. (2000). Diagnostic and statistical man- “loner” attacks from other domestic extremist violence: A comparison of ual of mental disorders (4th ed., text rev.). Washington, DC: American far-right homicide. Incident and offender characteristics. Criminology & Psychiatric Association. Public Policy, 12, 65–91. doi:10.1111/1745-9133.12009 Anderson, M. (1997). Mental illness and criminal behaviour: A literature Hauffe, S., & Porter, L. (2009). An interpersonal comparison of lone and review. Journal of Psychiatric and Mental Health Nursing, 4, 243–250. group rape offences. Psychology, Crime & Law, 15, 469 – 491. doi: doi:10.1046/j.1365-2850.1997.00061.x 10.1080/10683160802409339 Bijleveld, C., & Hendriks, J. (2003). Juvenile sex offenders: Differences Heskin, K. (1984). The psychology of terrorism in Ireland. In Y. Alexander between group and solo offenders. Psychology, Crime & Law, 9, 237– & A. O’Day (Eds.), Terrorism in Ireland (pp. 88 –105). New York: St. 245. doi:10.1080/1068316021000030568 Martin’s. Borum, R. (2004). Psychology of terrorism. Tampa: University of South Hewitt, C. (2003). Understanding terrorism in America. New York, NY: Florida. Borum, R. (2013). Informing lone-offender investigations. Criminology & Routledge. Public Policy, 12, 103–112. doi:10.1111/1745-9133.12016 Hickle, K. E., & Roe-Sepowitz, D. E. (2010). Female juvenile arsonists: Borum, R., Fein, R., & Vossekuil, B. (2012). A dimensional approach to An exploratory look at characteristics and solo and group arson offences. analyzing lone offender terrorism. Aggression and Violent Behaviour, Legal and Criminological Psychology, 15, 385–399. doi:10.1348/ 17, 389 –396. doi:10.1016/j.avb.2012.04.003 135532509X473913 Bueno de Mesquita, E. (2005). The quality of terror. American Journal of Hiday, V. A. (1995). The social context of mental illness and violence. Political Science, 49, 515–530. doi:10.1111/j.1540-5907.2005.00139.x Journal of Health and Social Behaviour, 36, 122–137. Retrieved from Chermak, S. M., Freilich, J. D., & Simone, J., Jr. (2010). Surveying http://www.jstor.org/stable/2137220 American state police agencies about lone wolves, far-right criminality Hiday, V. A., & Burns, P. J. (2010). Mental illness and the criminal justice and far-right and Islamic Jihadist criminal collaboration. Studies in system. In T. L. Scheid & T. N. Brown (Eds.), A handbook for the study Conflict & Terrorism, 33, 1019 –1041. doi:10.1080/1057610X.2010 of mental health: Social contexts, theories and systems (2nd ed., pp. 478 – 498). Cambridge, England: Cambridge University Press. Clarke, R. V., & Newman, G. R. (2006). Outsmarting the terrorists. Higgins, D. J., Bailey, S. R., & Pearce, J. C. (2005). Factors associated with Westport, CT: Praeger Security International, Greenwood Publishing functioning style and coping strategies of families with a child with an Group. autism spectrum disorder. Autism, 9, 125–137. doi:10.1177/ Coid, J. W., Ullrich, S., Keers, R., Bebbington, P., Destavola, B. L., Kallis, C.,... Donnelly, P. (2013). Gang membership, violence, and psychiatric Holcomb, W. R., & Ahr, P. R. (1988). Arrest rates among young adult morbidity. American Journal of Psychiatry, 170, 985–993. doi:10.1176/ psychiatric patients treated in inpatient and outpatient settings. Hospital appi.ajp.2013.12091188 and Community Psychiatry, 39, 52–57. Crenshaw, M. (1981). The causes of terrorism. Comparative Politics, 13, Horgan, J. (2005). The psychology of terrorism. London, England: Rout- 379 –399. doi:10.2307/421717 ledge. Douglas, K. S., Guy, L. S., & Hart, S. D. (2009). Psychosis as a risk factor James, D. V., Mullen, P. E., Meloy, J. R., Pathé, M. T., Farnham, F. R., for violence to others: A meta-analysis. Psychological Bulletin, 135, Preston, L., & Darnley, B. (2007). The role of mental disorder in attacks 679 –706. doi:10.1037/a0016311 on European politicians 1990 –2004. Acta Psychiatrica Scandinavica, Elbogen, E. B., & Johnson, S. C. (2009). The intricate link between 116, 334 –344. doi:10.1111/j.1600-0447.2007.01077.x violence and mental disorder: Results from the national epidemiologic Jenkins, B. M. (2013). Foreward. In J. D. Simon (Ed.), Lone wolf terror- survey on alcohol and related conditions. Archives of General Psychi- ism: Understanding the growing threat (pp. 7–11). New York, NY: atry, 66, 152–161. doi:10.1001/archgenpsychiatry.2008.537 Prometheus Books. Elisha, D., Castle, D., & Hocking, B. (2006). Reducing social isolation in Kendler, K. S., Karkowski, L. M., & Prescott, C. A. (1999). Causal people with mental illness: The role of the psychiatrist. Australasian relationship between stressful life events and the onset of major depres- Psychiatry, 14, 281–284. doi:10.1080/j.1440-1665.2006.02287.x sion. American Journal of Psychiatry, 156, 837– 841. Retrieved from Farrington, K. (1986). The application of stress theory to the study of http://journals.psychiatryonline.org/article.aspx?articleid173488 family violence: Principles, problems, and prospects. Journal of Family Kessler, R. C., Chiu, W. T., Demler, O., & Walters, E. E. (2005). Preva- Violence, 1, 131–147. doi:10.1007/BF00977249 lence, severity and comorbidity of 12-month DSM–IV disorders in the Fazel, S., & Danesh, J. (2002). Serious mental disorder in 23 000 prisoners: A systematic review of 62 surveys. The Lancet, 359, 545–550. doi: national comorbidity survey replication. Archives of General Psychiatry, 10.1016/S0140-6736(02)07740-1 62, 617–709. Retrieved from http://apsychoserver.psych.arizona.edu/ Fein, R. A., & Vossekuil, B. (1999). Assassination in the United States: An JJBAReprints/PSYC621/Kessler%20et%20al%20Arch%20Gen%20 operational study of recent assassins, attackers, and near-lethal ap- Psych%202005b.pdf This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly. CORNER AND GILL Krakowski, M., Volavka, J., & Brizer, D. (1986). Psychopathology and inpatients. American Journal of Psychiatry, 150, 1037–1042. Retrieved violence: A review of literature. Comprehensive Psychiatry, 27, 131– from http://ajp.psychiatryonline.org/article.aspx?articleID169610 148. doi:10.1016/0010-440X(86)90022-2 Scott, C. L., & Resnick, P. J. (2006). Violence risk assessment in persons Link, B. G., & Stueve, A. (1994). Psychotic symptoms and the violent/ with mental illness. Aggression and Violent Behavior, 11, 598 – 611. illegal behavior of mental patients compared to community controls. In doi:10.1016/j.avb.2005.12.003 J. Monahan & H. J. Steadman (Eds.), Violence and mental disorder: Shaw, J., Hunt, I. M., Flynn, S., Meehan, J., Robinson, J., Bickley, H.,... Developments in risk assessment (pp. 137–160). Chicago, IL: University Appleby, L. (2006). Rates of mental disorder in people convicted of of Chicago Press. homicide: National clinical survey. British Journal of Psychiatry, 188, McAdam, D. (1986). Recruitment to high-risk activism: The case of 143–147. doi:10.1192/bjp.188.2.143 Freedom Summer. American Journal of Sociology, 92, 64 –90. Retrieved Silke, A. (2003). Becoming a terrorist. In A. Silke (Ed.), Terrorists, victims from http://www.jstor.org/stable/2779717 and society: Psychological perspectives on terrorism and its conse- McCauley, C., Moskalenko, S., & Van Son, B. (2013). Characteristics of quences. Chichester, England: Wiley. lone-wolf violent offenders: A comparison of assassins and school Simcox, R., Stuart, H., Ahmed, H., Murray, D., & Carlile, A. (2011). attackers. Perspectives on Terrorism, 7, 4 –24. Retrieved from http:// Islamist terrorism: The British connections. London, England: Henry www.terrorismanalysts.com/pt/index.php/pot/article/view/240 Jackson Society. Meloy, J. R., Hempel, A. G., Gray, T., Mohandie, K., Shiva, A., & Singleton, N., Meltzer, H., & Gatward, R. (1998). Psychiatric morbidity Richards, T. C. (2004). A comparative analysis of North American among prisoners: Summary report. Government Statistical Service. Re- adolescent and adult mass murderers. Behavioural Sciences and the trieved from Office for National Statistics website: http://www.ons.gov Law, 22, 291–309. doi:10.1002/bsl.586 .uk/ons/rel/psychiatric-morbidity/psychiatric-morbidity-among-prisoners/ Meloy, J. R., Hempel, A. G., Mohandie, K., Shiva, A. A., & Gray, T. psychiatric-morbidity-among-prisoners-summary-report/index.html (2001). Offender and offense characteristics of a nonrandom sample of SMART. (2012). Sampling methods and sample size calculation for the adolescent mass murderers. Journal of the American Academy of Child SMART methodology. Retrieved from Humanitarian Response website: & Adolescent Psychiatry, 40, 719 –728. doi:10.1097/00004583- https://assessments.humanitarianresponse.info/document/sampling- 200106000-00018 methods-and-sample-size-calculation-smart-methodology Merari, A. (1990). The readiness to kill and die: Suicidal terrorism in the Spaaij, R. (2010). The enigma of lone wolf terrorism: An assessment. Middle East. In W. Reich (Ed.), Origins of terrorism (p. 192). Wash- Studies in Conflict & Terrorism, 33, 854 – 870. doi:10.1080/1057610X ington, DC: Woodrow Wilson Center Press. .2010.501426 Ministry of Justice. (2012). MAPPA guidance: Version 4. Retrieved from http:// Swanson, J., Holzer, C., Ganju, V. K., & Jono, R. T. (1990). Violence and www.justice.gov.uk/downloads/offenders/mappa/mappa-guidance-2012-part1 psychiatric disorder in the community: Evidence from the epidemiologic .pdf catchment area surveys. Hospital & Community Psychiatry, 41, 761– Mother Jones. (2013). Profiles in terror. Retrieved from http://www 770. Retrieved from http://ps.psychiatryonline.org/article.aspx? .motherjones.com/fbi-terrorist articleID74352 Ouzir, M. (2013). Impulsivity in schizophrenia: A comprehensive update. Teplin, L. A. (1984). Criminalizing mental disorder: The comparative Aggression and Violent Behavior, 18, 247–254. doi:10.1016/j.avb.2012 arrest rate of the mentally ill. American Psychologist, 39, 794 – 803. .11.014 doi:10.1037/0003-066X.39.7.794 Post, J. M. (2005). Psychology. In P. R. Neumann (Ed.), Addressing the Thoits, P. A. (1983). Multiple identities and psychological well-being: A causes of terrorism: The Club de Madrid series of democracy and reformulation and test of the social isolation hypothesis. American terrorism (Vol. 1, pp. 7–12). Madrid, Spain: Club de Madrid. Sociological Review, 48, 174 –187. Retrieved from http://www.jstor.org/ Post, J., Sprinzak, E., & Denny, L. (2003). The terrorists in their own stable/2095103?seq1&uid3738032&uid2&uid4&sid21104017 words: Interviews with 35 incarcerated Middle Eastern terrorists. Ter- rorism and political Violence, 15, 171–184. doi:10.1080/ Todd, J., Green, G., Harrison, M., Ikuesan, B. A., Self, C., Pevalin, D. J., & Baldacchino, A. (2004). Social exclusion in clients with comorbid Rasch, W. (1979). Psychological dimensions of political terrorism in the mental health and substance misuse problems. Social psychiatry and Federal Republic of Germany. International Journal of Law and Psy- psychiatric epidemiology, 39, 581–587. doi:10.1007/s00127-004-0790-0 chiatry, 2, 79 – 85. doi:10.1016/0160-2527(79)90031-1 Victoroff, J. (2005). The mind of the terrorist: A review and critique of Reinares, F. (2004). Who are the terrorists? Analyzing changes in socio- psychological approaches. The Journal of Conflict Resolution, 49, 3– 42. logical profile among members of ETA. Studies in Conflict and Terror- doi:10.1177/0022002704272040 ism, 27, 465– 488. doi:10.1080/10576100490519741 World Health Organization. (2010). ICD-10: International statistical clas- Roberts, A. L., McLaughlin, K. A., Conron, K. J., & Koenen, K. C. (2011). sification of diseases and related health problems (10th review). Re- Adulthood stressors, history of childhood adversity, and risk of perpe- trieved from http://www.who.int/classifications/icd/en/ tration of intimate partner violence. American Journal of Preventive Medicine, 40, 128 –138. doi:10.1016/j.amepre.2010.10.016 Sageman, M. (2005). Understanding terror networks. Philadelphia: Uni- Received January 27, 2014 versity of Pennsylvania Press. Revision received June 17, 2014 Saxe, G. N., van der Kolk, B. A., Berkowitz, R., Chinman, G., Hall, K., Lieberg, G., & Schwartz, J. (1993). Dissociative disorders in psychiatric Accepted June 19, 2014 This document is copyrighted by the American Psychological Association or one of its allied publishers. This article is intended solely for the personal use of the individual user and is not to be disseminated broadly.
Law and Human Behavior – American Psychological Association
Published: Feb 18, 2015
You can share this free article with as many people as you like with the url below! We hope you enjoy this feature!
Read and print from thousands of top scholarly journals.
Already have an account? Log in
Bookmark this article. You can see your Bookmarks on your DeepDyve Library.
To save an article, log in first, or sign up for a DeepDyve account if you don’t already have one.
Copy and paste the desired citation format or use the link below to download a file formatted for EndNote
Access the full text.
Sign up today, get DeepDyve free for 14 days.
All DeepDyve websites use cookies to improve your online experience. They were placed on your computer when you launched this website. You can change your cookie settings through your browser.