Washington, DC - The Office of Justice Programs’ National Institute of Justice (NIJ) Friday published an article discussing the NIJ-supported and publicly available Violence Project Database that identifies common traits of persons who engaged in mass shootings between 1966 and 2019.

During that time, mass shootings in the United States notably increased, with more than half occurring after 2000, and 20% occurring during the last five years of the study period. The death toll in mass shootings in the last decade has grown dramatically. In the 1970s, mass shootings claimed an average of eight lives per year. From 2010 to 2019, the average was 51 deaths per year.

“This study — one of the most extensive assessments of mass violence to date—reveals a deeply unsettling trend: more Americans are dying at the hands of mass shooters than at any point in recent history,” said OJP Principal Deputy Assistant Attorney General Amy L. Solomon. “This analysis paints a portrait of shooters, giving us a better idea of who commits these crimes and helping us detect the warning signals for these appalling acts of violence.”

The database draws information exclusively from open sources, such as social media sites and online newspapers, in order to build a broader understanding on the part of the public, the justice system and the research community of who mass shooters are and what motivates them. Funded by NIJ, it covers 172 mass public shooters and more than 150 psychosocial history variables, such as those individuals’ mental health history, past trauma, interest in past shootings and situational triggers.

Analysis of the database shows that persons who committed public mass shootings in the U.S. over the last half century were commonly troubled by personal trauma before the shooting, nearly always in a state of crisis at the time and, in most cases, engaged in leaking their plans before opening fire. Most were insiders of a targeted institution, such as an employee or student. Except for young school shooters who stole the guns from family members, most used legally obtained handguns in those shootings.

The study includes a discussion of demographics, motivations, warning signs and other key findings. The article is available at “Public Mass Shootings: Database Amasses Details of a Half Century of U.S. Mass Shootings with Firearms, Generating Psychosocial Histories.” The research described in this article is based on the grantee report, A Multi-Level, Multi-Method Investigation of the Psychosocial Life Histories of Mass Shooters, September 2021, by Co-Principal Investigators Jillian Peterson and James Densley.