The lessons BTAC learned from the study revealed similar findings from other past FBI and academic research on pre-attack behaviors, stressors, and risk factors exhibited and experienced by previous attackers. The BTAC discovered that while the attackers in the study were ideologically motivated lone offenders, they were rarely completely isolated and alone. The report also found that while predicting lone offender terrorism is not possible, it may be preventable with increased bystander education and awareness in recognizing concerning behavior and reporting it to authorities as soon as possible.

Of the 52 examined cases between 1972 and 2015, 83% were carried out by people who had previously exhibited hostility or aggression, according to the 81-page report. In all of the cases, people around the attackers expressed concern over their behavior.

In 96% of the cases, the offender produced a video, blog or letter that was intended to be viewed by others.

“The FBI’s research in the Lone Offender Terrorism Report is an invaluable tool not only for the FBI but for our law enforcement partners and other multi-disciplinary threat assessment teams,” said Assistant Director John Selleck of the FBI’s Critical Incident Response Group. “It is also our goal that this report successfully enhances the public’s education and awareness of these types of attacks. By closely studying past lone offender behaviors and sharing the findings, we enhance our collective efforts to prevent future attacks and save lives.”