The Swedish School Attack in Trollhättan

Erlandsson, Åsa; Meloy, J. Reid

doi:10.1111/1556-4029.13800

Cited by 19 publications

(25 citation statements)

References 11 publications

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“…There are no empirically derived cutoffs for the TRAP-18 since it is a structured professional judgment instrument and not a psychological test. Nevertheless, the model advances the hypothesis that one proximal warning behavior is necessary for active risk management, and data indicate that all targeted violence subjects to date have exhibited multiple warning behaviors prior to their attacks (Böckler et al, 2021;Meloy, 2018;Meloy et al, 2019).…”

Section: Measurement Instrumentmentioning

confidence: 91%

Time sequencing the TRAP-18 indicators.

Meloy¹,

Goodwill²,

Clemmow³

et al. 2021

Journal of Threat Assessment and Management

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A time sequence analysis is conducted on 125 lone actor terrorists, most of whom mounted attacks in Europe and North America, utilizing the TRAP-18 (Terrorist Radicalization Assessment Protocol), a structured professional judgment instrument with demonstrable interrater reliability and criterion, discriminant, and predictive validity. Both frequency filters (>3) and coefficient filters (>.50) were applied to the data. Results indicate that virtually all distal characteristics, such as criminal violence, mental disorder, and ideology, preceded the proximal warning behaviors, such as pathway, fixation, identification, leakage, last resort, and directly communicated threats. Indicators that were "gatekeepers" and "turning point events" were also identified (Taylor et al., 2008). The time sequence analysis further validates the model of the TRAP-18 as a risk instrument for the assessment and management of lone actor terrorist violence. Public Interest StatementThis study applies a terrorist risk assessment instrument, the TRAP-18, to a large sample of lone actor terrorists using time sequence analysis: a method by which indicators of risk are organized in a temporal relationship with one another. It allows counterterrorism investigators to better understand the unfolding of risk indicators over time on the way to a terrorist attack, and helps prioritize the most dangerous cases.

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Section: Measurement Instrumentmentioning

confidence: 91%

Time sequencing the TRAP-18 indicators.

Meloy¹,

Goodwill²,

Clemmow³

et al. 2021

Journal of Threat Assessment and Management

View full text Add to dashboard Cite

show abstract

“…Hemmingby and Bjorgo (2018) examine the impact of psychological make-up upon one terrorist attack using unique access to police and investigative files. Other in-depth case studies look at the impact of mental health crises upon the adoption of violent extremist views also (Gill, 2015;Holt et al, 2018;Erlandsson & Meloy, 2018;.…”

Section: Theme 4: From Presence To Relevancementioning

confidence: 99%

Systematic Review of Mental Health Problems and Violent Extremism

Gill¹,

Clemmow²,

Hetzel³

et al. 2020

The Journal of Forensic Psychiatry & Psychology

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A wide range of studies investigating the nature and determinants of radicalisation, and terrorist-related behaviour exist. These, in turn, have influenced theory, policy and practice in areas concerned with violent extremism prevention, disruption and management. As such interventions become more common, debates rage within mental health professions about the role mental health practitioners should play in countering violent extremism. This systematic review assesses the impact of mental health problems upon attitudes, intentions and behaviours in the context of radicalisation and terrorism. We identified 25 studies that measured rates of mental health problems across 28 samples. The prevalence rates are heterogenous and range from 0% to 57%. If we pool the results of those samples (n=19) purely focused upon confirmed diagnoses where sample sizes are known (n=1705 subjects), the results suggest a rate of 14.4% with a confirmed diagnosis. Where studies relied upon wholly, or in some form, upon privileged access to police or judicial data, diagnoses occurred 16.96% of the time (n=283 subjects). Where studies were purely focused upon open sources (n=1089 subjects), diagnoses were present 9.82% of the time. We then explore (a) the types and rates of mental health disorders identified (b) comparison/control group studies (c) studies that explore causal roles of mental health problems and (d) other complex needs.

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“…The instrument has been shown to have excellent interrater reliability (Challacombe & Lucas, 2018;Meloy, Roshdi,, et al, 2015) and criterion validity on samples of individual terrorists and autonomous terrorist cells (Meloy & Gill, 2016;Meloy, Roshdi, et al, 2015). Its growing construct validity has been extended through its operational usefulness in the retrospective analysis of a number of individual cases of lone actor terrorism (Bockler, Hoffmann, & Meloy, 2017;Bockler, Hoffmann, & Zick, 2015;Erlandsson & Meloy, 2018;Meloy & Genzman, 2016;Meloy, Habermeyer, & Guldimann, 2015). The warning behaviorsthe first eight indicators in the TRAP-18have been shown to have discriminant validity with medium to large effect sizes in separating school attackers from other subjects of concern with no intent to attack (Meloy, Hoffmann, Roshdi, & Guldimann, 2014), and the TRAP-18 in toto was successful in postdicting violence with 76% accuracy within a sample of Sovereign Citizens, an extreme right wing group in the US (Challacombe & Lucas, 2018).…”

Section: Measurement Instrumentmentioning

confidence: 99%

Visualizing the relationship among indicators for lone actor terrorist attacks: Multidimensional scaling and the TRAP‐18

Goodwill

Meloy

2019

Behavioral Sci & The Law

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This validation study analyses data from a sample of North American terrorist attackers (n = 33) and non‐attackers (n = 23) through the lens of the Terrorist Radicalization Assessment Protocol (TRAP‐18; Meloy, 2017) utilizing a multivariate statistical approach – multidimensional scaling – to visualize potential clustering (co‐occurrence) of risk factors. Rarely done in terrorism research, the results plotted in two‐dimensional space show the clustering and co‐occurrence of most of the eight proximal warning behaviors among the attackers, but not among the non‐attackers, and less of a clustering and association of distal characteristics, but their presence in both attackers and non‐attackers. These findings provide further empirical support for the rational‐theoretical model of the TRAP‐18, a structured professional judgment instrument for threat assessment of lone actor terrorists. It advances the quantitative analysis of operationally relevant and behaviorally observable indicators for use by law enforcement and counterterrorism professionals and their consultants. Findings are discussed in relation to other research on pre‐offense behaviors of lone actor terrorists, and recommendations are made for both operational use and further research.

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The Swedish School Attack in Trollhättan

Cited by 19 publications

References 11 publications

Time sequencing the TRAP-18 indicators.

Time sequencing the TRAP-18 indicators.

Systematic Review of Mental Health Problems and Violent Extremism

Visualizing the relationship among indicators for lone actor terrorist attacks: Multidimensional scaling and the TRAP‐18

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