Family mass murder in the United States, 1970-2019: Perpetrator mental health characteristics and the role of domestic violence.

Examining perpetrator characteristics of, and risk factors for, different types of mass murder, such as family mass murder-the most common type-could have important ramifications for preventive efforts. Histories of domestic violence and mental illness are of particular interest. We examined 944 cases of mass murder from the Columbia Mass Murder Database that occurred in the United States between 1970 and 2019, identifying 377 incidents (39.9%) in which at least one victim was a family member of the perpetrator. We collected information on histories of domestic violence and characteristics of mental illness among perpetrators from media reports and court and police records. Overall, 202 (21.4%) cases included histories of domestic violence. Firearms were used in four-fifths (759/944; 80.4%) of all cases of mass murder, while family mass murder was significantly less likely than other mass murder events to involve firearms (74.8% vs. 84.1%, χ2 12.5, p < 0.001). Perpetrators of family mass murder were significantly more likely to take their own lives at the time of the event than were other personal-cause mass-murder perpetrators (43.8% vs. 16.8%, χ2 82.8, p < 0.001). These data extend findings on differences between family mass murder and other types of mass murder when the three-victim definition is used. This study further supports previous reports of the limited contribution of both psychotic and non-psychotic mental health conditions to all types of mass murder, including family mass murder, and that policies focused elsewhere may be more effective at stemming the tide of all types of mass murder, including family mass murder.