The International Handbook of Threat Assessment, Second Edition: A Book Review

Clare S. Allely (Department of Forensic Psychology, University of Salford, Manchester, UK)

Journal of Criminal Psychology

ISSN: 2009-3829

Article publication date: 19 May 2022

Issue publication date: 19 May 2022



Allely, C.S. (2022), "The International Handbook of Threat Assessment, Second Edition: A Book Review", Journal of Criminal Psychology, Vol. 12 No. 1/2, pp. 26-30.



Emerald Publishing Limited

Copyright © 2022, Emerald Publishing Limited

Our ability to accurately predict the risk of an individual committing an act of targeted violence is likely to be impossible. One of the primary reasons for this is, thankfully, the very low base rate of these acts (Goodwill and Meloy, 2019). Nevertheless, prevention is possible if there is a focus on fact-based behaviours, and threat management is in place. As a researcher in the field of extreme violence, I have long been interested in studying the pathway to intended violence in mass shooters and lone actor terrorists. With my colleague, Dr Lino Faccini, we have explored the pathway to intended violence in a number of mass shooters/lone actors including Anders Breivik (Faccini and Allely, 2016a); Elliot Rodger (Allely and Faccini, 2017); Dylann Roof (Allely and Faccini, 2019); and Dean Allen Mellberg (Faccini and Allely, 2016b). We identify some of the pathway behaviours, warning signs, etc.

However, it is only in the last year that I have been properly introduced to and understood the importance of also including a threat assessment perspective in the work in this field. Up until this point, I had incorrectly assumed (embarrassing now when I look back) that risk assessment and threat assessment were similar and they had different names depending on the profession (e.g. risk assessment if in the context of psychology and psychiatry and threat assessment if in the context of law enforcement). I have since discovered that many individuals in the field of psychology and psychiatry are unaware or uncertain of the differences and similarities between risk assessment and threat assessment. I was delivering some training online earlier this year hosted by the Aurora Police Department in the USA on the pathway to intended violence in mass shooters. During my preparation for this training series, I met online with Dr Stephen White, who is co-author of the Workplace Assessment of Violence Risk (WAVR-21) and delivers training on violence risk and threat assessment in workplace, campus and community settings using the WAVR-21. Specifically, the WAVR-21 is a structured professional guide designed for mental health professionals and workplace-based threat management team members in security, education, human resources, law enforcement and mental health. Dr White is also author of a number of interesting papers in the field (White, 2017; White et al., 2017). Dr White introduced me to the key literature and concepts in the field of threat assessment and I have become immersed and fascinated by the field of threat assessment ever since.

So how do threat assessment and violence risk assessment differ exactly? They are similar, but each focuses on different aspects. Specifically, the main focus of threat assessment and management is on the identification, assessment and management of a person of concern in real time. In threat assessment and management, there is particular attention given to the target and the situation. On the other hand, traditional “violence risk assessment” involves the “determination of relative risk in an individual at a particular point in time by determining the base rate of violence for the group within which he or she belongs” (Guldimann and Meloy, 2020, p. 160). Therefore, the threat assessment and management approach is typically more dynamic and urgent. The risk assessment approach, on the other hand, is more of a static process (Guldimann and Meloy, 2020). In threat assessment, Meloy et al. (2015) state that a precise mental health diagnosis has “little incremental validity when threat assessing a person who warrants concern that he might perpetrate an act of intended or targeted violence, but greater relevance when threat managing a case” (pp. 165). Studies indicate that what is important to assess in an individual presenting with, for example, psychosis, is the level of positive symptoms and their “relationship to the motivation for violence” (Meloy et al., 2015).

Immersing myself in the field of threat assessment since my discussion with Dr White, I have also become really interested in The Terrorist Radicalization Assessment Protocol (TRAP-18; Meloy et al., 2015; Meloy and Gill, 2016; Meloy, 2017, 2018). The TRAP-18 is a collection of 18 behaviour-based warning signs for terror incidents. There are eight proximal characteristics and ten distal characteristics. The eight proximal characteristics are those that typically are exhibited closer in time to the incident. On the other hand, the ten distal characteristics are those that are usually developed over time and are more distantly related to the act for which there is concern (Meloy and Gill, 2016; Meloy et al., 2015). The eight proximal warning behaviours (Meloy and Gill, 2016; Meloy et al., 2015) are:

  1. pathway (attack research, planning or implementation);

  2. fixation;

  3. identification (self-identification as a fighter/warrior/agent of change);

  4. novel aggression;

  5. energy burst;

  6. leakage;

  7. last resort; and

  8. directly communicated threat.

These warning signs were identified through a number of case studies, interviews and empirical research (Meloy and Gill, 2016). The eight warning behaviours capture behavioural or psychological patterns that constitute change and may evidence accelerating risk – they should be considered as patterns for analysis as opposed to being discrete variables. They contain dynamic as opposed to static factors. Dynamic factors tend to offer more substantial contributions to the assessment and management of short-term violence, which is usually the focus of threat assessment (Douglas and Skeem 2005; Guldimann and Meloy, 2020).

In the TRAP-18, the ten distal characteristics focus on the individual’s lone-actor status. The ten distal characteristics are:

  1. personal grievance and moral outrage;

  2. framed by an ideology (justifying beliefs for action);

  3. failure to affiliate with an extremist group;

  4. dependence on virtual community;

  5. thwarting of occupational goals (setback/failure in academic/life pursuits);

  6. changes in thinking and emotions;

  7. failure of sexual-intimate pair bonding (individual fails to sexually or intimately bond);

  8. mental disorder;

  9. greater creativity and innovation; and

  10. criminal violence (Meloy and Gill, 2016).

It is important to emphasise that the TRAP-18 should not be considered or used as a psychological test or an actuarial risk assessment instrument.

Given my growing interest in the field of threat assessment and integrating this with risk assessment, I purchased a copy of The International Handbook of Threat Assessment, second edition, which came out this year. It is edited by J. Reid Meloy (editor), Clinical Professor, Department of Psychiatry, University of California, San Diego, School of Medicine, and also Jens Hoffmann (editor), Forensic Psychologist and Head, Institute of Psychology and Threat Management. The International Handbook of Threat Assessment is a vital read. It is practical and cross-disciplinary and should be read by all involved in both threat assessment and management and also risk assessment. The second edition of this international handbook is nearly double the size of the first edition. It is a comprehensive handbook aimed at both researchers and operators as the foundation textbook in this field. The handbook is divided into three sections, which collectively consist of 38 chapters:

  1. Foundations.

  2. Fields of practice.

  3. Operations.

The chapters in the first section of the international handbook include: Threat Assessment and Threat Management by J. Reid Meloy, Jens Hoffmann, Eugene R. D. Deisinger and Stephen D. Hart; Explicit Threats of Violence by Lisa J. Warren, Ruby Z. Basocak, Tamara Bobera, Sarah J. Chamberlain, Paul E. Mullen and Troy E. McEwan; Warning Behaviors by J. Reid Meloy, Jens Hoffmann, Lynne Bibeau and Angela Guldimann; Source Interviewing in a Threat Management Context by Bram B. Van der Meer; and Legal Issues in Threat Assessment and Management by Molly Amman, Ronald Schouten and Rachel B. Solov.

Some of the chapters in the Fields of practice section include: Workplace Targeted Violence: Assessment and Management in Dynamic Contexts by Stephen G. White; Threat Assessment and Management in K-12 Schools by Dewey G. Cornell and Anna Grace Burnette; Stalking Threat and Risk Assessment by Troy E. McEwan; Lone Actor Terrorism by Paul Gill; Crawling in the Dark – Perspectives on Threat Assessment in the Virtual Sphere by Mirko Allwinn and Nils Böckler; Fundamentals of Threat Assessment for Beginners by Mary Ellen O’Toole; International Legal Perspectives on Threat Assessment by Kris Mohandie and Jens Hoffmann; Rethinking the Path to Intended Violence by Frederick S. Calhoun and Stephen W. Weston; and The Importance of Bystanders in Threat Assessment and Management by Randy Borum and Mary Rowe.

Some of the chapters included in the Operations section of the international handbook include: Enhancing School Safety Using a Threat Assessment Model: An Operational Chapter for Preventing Targeted School Violence by Lina Alathari, Ashley Blair, Catherine Camilletti, Steven Driscoll, Diana Drysdale, Jeffrey McGarry and Amanda Snook; Operations of the Los Angeles Police Department Threat Management Unit and Crisis Support Response Section by Brian S. Bixler, Jeffrey Dunn and Traci Grundland; Domestic Violence Risk Assessment: Tools and Procedures for Threat Assessment and Management by Liam Ennis and N. Zoe Hilton; Threat Triage: Recognizing the Needle in the Haystack by Sharon S. Smith and Michael D. Young; Digital Behavioral Criminalistics to Elucidate the Cyber Pathway to Intended Violence by Cameron H. Malin; Making Sense of Terrorist Violence and Building Psychological Expertise by Monica Lloyd; and Assessing Threats by Direct Interview of the Violent True Believer by J. Reid Meloy and Kris Mohandie.

As mentioned on the website of this handbook, this volume’s contributors include virtually all experts from the global community. New areas of work are emphasized, including lone actor terrorism, cyberthreats, insider threats, false allegations and bystanders. Established areas of work are further delineated, including workplace violence, stalking, public figure threats and attacks, direct threats of violence, proximal warning behaviours, legal issues in management, domestic violence threat assessment, honour-based violence, source interviewing and evidence-based threat management in both secondary education and university settings.

The second edition of the International Handbook of Threat Assessment includes chapters looking at a range of areas including national security (international terrorism, lone offender terrorism, insider threats), stalking and intimate partner violence, school- and work-based threat assessment, identification of anonymous threats, digital and electronic case review and analysis, public figure attacks, honor killings, roles of bystanders in threat assessment and legal issues and concerns. This international handbook is essential to any professional who is concerned with the prevention of targeted violence and I cannot emphasise the importance of it enough.


Allely, C.S. and Faccini, L. (2017), “‘Path to intended violence’ model to understand mass violence in the case of Elliot Rodger”, Aggression and Violent Behavior, Vol. 37, pp. 201-209.

Allely, C.S. and Faccini, L. (2019), “Clinical profile, risk, and critical factors and the application of the ‘path toward intended violence’ model in the case of mass shooter Dylann roof”, Deviant Behavior, Vol. 40 No. 6, pp. 672-689.

Douglas, K.S. and Skeem, J.L. (2005), “Violence risk assessment: getting specific about being dynamic”, Psychology, Public Policy, and Law, Vol. 11 No. 3, pp. 347-383.

Faccini, L. and Allely, C.S. (2016a), “Mass violence in individuals with autism spectrum disorder and narcissistic personality disorder: a case analysis of Anders Breivik using the ‘path to intended and terroristic violence’ model”, Aggression and Violent Behavior, Vol. 31, pp. 229-236.

Faccini, L. and Allely, C.S. (2016b), “Mass violence in an individual with an autism spectrum disorder: a case analysis of dean Allen Mellberg using the ‘path to intended violence’ model”, International Journal of Psychological Research, Vol. 11 No. 1, pp. 1-18.

Goodwill, A. and Meloy, J.R. (2019), “Visualizing the relationship among indicators for lone actor terrorist attacks: multidimensional scaling and the TRAP‐18”, Behavioral Sciences & the Law, Vol. 37 No. 5, pp. 522-539.

Guldimann, A. and Meloy, J.R. (2020), “Assessing the threat of lone-actor terrorism: the reliability and validity of the TRAP-18”, Forensische Psychiatrie, Psychologie, Kriminologie, Vol. 14 No. 2, pp. 158-166.

Meloy, J.R. (2017), The TRAP-18 Manual Version 1.0, Global Institute of Forensic Research, Washington, DC.

Meloy, J.R. (2018), “The operational development and empirical testing of the terrorist radicalization assessment protocol (TRAP–18)”, Journal of Personality Assessment, Vol. 100 No. 5, pp. 483-492.

Meloy, J.R. and Gill, P. (2016), “The lone-actor terrorist and the TRAP-18”, Journal of Threat Assessment and Management, Vol. 3 No. 1, pp. 37-52.

Meloy, J.R., Habermeyer, E. and Guldimann, A. (2015), “The warning behaviors of Anders Breivik”, Journal of Threat Assessment and Management, Vol. 2 Nos 3/4, pp. 164-175.

White, S.G. (2017), “Case study: the Isla vista campus community mass murder”, Journal of Threat Assessment and Management, Vol. 4 No. 1, p. 20.

White, S.G., Meloy, J.R., Mohandie, K. and Kienlen, K. (2017), “Autism spectrum disorder and violence: threat assessment issues”, Journal of Threat Assessment and Management, Vol. 4 No. 3, p. 144.

About the author

Clare S. Allely is Reader in the Department of Forensic Psychology, University of Salford, Manchester, UK. She is a Reader in Forensic Psychology at the University of Salford in Manchester, UK, and is an affiliate member of the Gillberg Neuropsychiatry Centre at Gothenburg University, Sweden. Clare holds a PhD in Psychology from the University of Manchester and has previously graduated with an MA (hons.) in Psychology from the University of Glasgow, an MRes in Psychological Research Methods from the University of Strathclyde and an MSc in Forensic Psychology from Glasgow Caledonian University. Clare is also an Honorary Research Fellow in the College of Medical, Veterinary and Life Sciences, affiliated to the Institute of Health and Wellbeing at the University of Glasgow. She is also an Associate of The Children’s and Young People’s Centre for Justice (CYCJ) at the University of Strathclyde. Clare also acts as an expert witness in criminal cases and also contributes to the evidence base used in the courts on psychology and legal issues through her published work.

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