Journal of Threat Assessment and Management, Vol 12(3), Sep 2025, 178-196; doi:10.1037/tam0000240
Some perpetrators of serious targeted violence publish self-testimonies in the period leading up to their attack, expressing their intention to commit a violent act. This is especially true for so-called “fame seeking mass shooters.” This single case study examines whether such materials offer opportunities for threat assessment. For this purpose, publicly available documents of the online activities of an American rampage killer were examined on a large scale for the presence of any warning behaviors using Meloy’s et al. (2012) warning behavior typology. The material included posts that had been published on YouTube, Twitter, and a Columbine fan forum long before the crime. Furthermore, there were self-testimonies in the form of audio files and scanned diary pages that he had uploaded immediately before the shooting. Our analyses show that seven out of eight warning behaviors were clearly identifiable from these materials. The potential for making such perpetrator documents usable for threat mitigation is discussed. (PsycInfo Database Record (c) 2025 APA, all rights reserved)