The Violence Project Mass Shooter Database already included over 170 mass shooters who killed 4 or more people in a public setting since 1966 coded on 100 pieces of life history information. This update adds 50 new items for journalists, researchers, students, and policymakers to interact with. The goal of this project is to provide data to ground our public policy conversations and to develop data-driven prevention strategies.
The Violence Project Mass Shooter Database was funded by the
Version 2.0 of the database is being released to coincide with the one-year anniversary of the mass shootings in
The new database also includes extended information on "leakage" (communication to a third party of an intent to do harm). Most shooters who leaked their plans did so in person to their wives, coworkers, and friends, the data show. School shooters were most likely to leak their plans ahead of time and did so in every case but one.
There have been far fewer opportunities for mass shootings to occur this year with public spaces closed and people in lockdown, with only one new case in 2020—the Milwaukee
Over 80% of mass shooters were in a noticeable crisis prior to their shooting. The new database breaks down that crisis into its component parts, like increased agitation, isolation, mood swings, and paranoia. The role of psychosis in mass shootings is also better accounted for. Psychosis directly motivated a mass shooting in 11% of cases, but 70% of the time, psychosis played no role at all. In 19% of mass shootings, psychosis played some role, but the shooter had other motives.
Other new items include a history of domestic violence (33% of perpetrators), a measure of firearm proficiency (higher proficiency was correlated with more deaths), violent video game playing, hate group association, childhood socioeconomic status, past school performance, community involvement, and information on siblings (mass shooters were most likely to be youngest children).