An analysis of 105 female-perpetrated mass murders.

Most research on mass murderers to date has focused on perpetrators of male sex, while research on perpetrators of female sex has been relegated to case reports and series. We aimed to more fully examine the phenomenon of female-perpetrated mass murder. We analyzed 1715 worldwide incidents of personal-cause mass murder from 1900 to 2019, identifying 105 (6%) events perpetrated by females. We defined mass murder as any event involving at least three fatalities, not including the perpetrator, using any method. We identified cases of mass murder from English-language databases of mass murder or murder in print or online. There were no significant differences in age and race between female and male perpetrators. Relative to males, female perpetrators were significantly less likely to employ firearms in their mass murders, using them in less than half of cases, compared to over 70% for males. The prevalence of psychotic signs and symptoms among female mass murderers was more than double that among males (25.7% vs. 12.5%, p < 0.01), while the rate of nonpsychotic psychiatric or neurological conditions was also much greater among female perpetrators (29.5% vs. 17.1%, p < 0.01). Over half of female perpetrators took or attempted to take their own lives. More than three-quarters of mass murders by females involved at least one family member as a victim. This study underscores sex-specific differences in the perpetration of mass murder and the need for further research to understand how insights about such dynamics might lead to the development of more effective and informed intervention policies.