The lone-actor terrorist and the TRAP-18.

Abstract

An open source sample of 111 lone-actor terrorists from the United States and Europe were studied through the lens of the Terrorist Radicalization Assessment Protocol (TRAP-18). This investigative template consists of 8 proximal warning behaviors and 10 distal characteristics for active risk management or active monitoring, respectively, by national security threat assessors. Several aspects of criterion validity were tested in this known outcome sample. Seventy percent of the terrorists were positive for at least half or more of the indicators. When the sample was divided into Islamic extremists, right-wing extremists, and single-issue terrorists, there were no significant differences across all 18 indicators except for 4. When the sample was divided according to successful versus thwarted attackers, the successful attackers were significantly more fixated, creative, and innovative, and failed to have a prior sexually intimate pair bond. They were significantly less likely to have displayed pathway warning behavior and be dependent on a virtual community of likeminded true believers. Effect sizes were small to medium (ϭ 0.190-0.317). The TRAP-18 appears to have promise as an eventual structured professional judgment risk assessment instrument according to some of the individual terrorist content domains outlined by Monahan (2012, 2016).

Same but Different? Developmental Pathways to Demonstrative Targeted Attacks — Qualitative Case Analyses of Adolescent and Young Adult Perpetrators of Targeted School Attacks and Jihadi Terrorist Attacks in Germany

“…The perpetrator increasingly moves into a phase of clandestine planning characterized by a state of tension between secret private rituals and public intimation (leakage) (Gill, 2015; Meloy & O’Toole, 2011; Meloy, Mohandie, Knoll, & Hoffmann, 2015). Many investigators have been able to reconstruct different trigger events after which the perpetrator might view the act of violence as necessary, justified, inevitable, and meaningful (Corner & Gill, 2015; Heitmeyer, Böckler, & Seeger 2013; Meloy & Gill, 2016). …”

Terrorism, Radicalisation, Extremism, Authoritarianism and Fundamentalism: A Systematic Review of the Quality and Psychometric Properties of Assessments

“…Instruments to be used operationally by professionals included the VERA-2 with two distinct studies [14, 15], ERG 22+ [16], ERS [16] and IVPG with two distinct studies [17]. The tools developed as research measures of particular constructs were the 1992-RWA [6], RF-R [18], PHS [19], MMPI-2 [19], RWA-R [20], ITFS [21], ARIS [22], NBMASA [23], MEMS [24], MDFI [25], RF-I [26], SyfoR [27], IFS [28], SSS [29], ARIS-S [30], TCS [31], TRAP-18 [32] and a tool created by Schbley [33]. Finally, inventories not generated from a study comprised tools developed by Ross [34], Vaisman-Tzachor [35], Horgan [36], Saucier et al [37], Kebbell and Porter [38], Monahan [39], USAID [40], Borum [41] and the EMI-20 [42].…”

Lone‐actor Terrorism and Impulsivity

“…However, his radicalization to violence unfolded in behavior that was evident for months, if not years: Johnson was a member of the Houston chapter of the New Black Panther Party several years earlier, listed by the Southern Poverty Law Center as a hate group. He was asked to leave this group because of his dangerous rhetoric and desire for the group to purchase more weapons and ammunition, a failure to affiliate . On July 2, he posted an angry and disjointed statement against White people on Facebook.…”