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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. [ABSTRACT FROM AUTHOR]

Mass murder, particularly mass shootings, constitutes a major, growing public health concern. Specific motivations for these acts are not well understood, often overattributed to severe mental illness. Identifying diverse factors motivating mass murders may facilitate prevention. We examined 1,725 global mass murders from 1900–2019, publicly described in English in print or online. We empirically categorized each into one of ten categories reflecting reported primary motivating factors, which were analyzed across mass murderers generally, as well as between U.S- and non-U.S.-based mass-shooters. Psychosis or disorganization related to mental illness were infrequently motivational factors (166; 9.6%), and were significantly more associated with mass murder committed using methods other than firearms. The vast majority (998, 57.86%) of incidents were impulsive and emotionally-driven, following adverse life circumstances. Most mass murderers prompted by emotional upset were found to be driven by despair or extreme sadness over life events (161, 16.13% within the category); romantic rejection or loss, or severe jealousy (204, 20.44% within the category); some specific non-romantic grudge (212, 21.24% within the category); or explosive, overwhelming rage following a dispute (266, 26.65% within the category). Results suggest that policies seeking to prevent mass murder should focus on criminal history, as well as subacute emotional disturbances not associated with severe mental illness in individuals with poor coping skills who have recently experienced negative life events. [ABSTRACT FROM AUTHOR]

Most research to date has focused on perpetrators of mass murder incidents. Hence, there is little information on victims. We examined 973 mass murders that occurred in the United States between 1900 and 2019 resulting in 5,273 total fatalities and 4,498 nonfatal injuries for a total of 9,771 victims (on average 10 victims per incident). Approximately 64% of victims of mass murder were White individuals, 13% were Black individuals, 6% were Asian individuals, and 14% were Latinx individuals. Given the higher number of nonfatal injuries per non-firearm mass murder event (11.0 vs. 2.8, p <.001), the total number of victims was only 50% higher for mass shootings (5,855 victims) vs. non-firearm mass murder events (3,916 victims). Among the 421 incidents of mass murder in the United States since 2000, Black, Asian, and Native American individuals were overrepresented among victims of mass shootings compared with their representation in the general U.S. population, and White individuals were underrepresented (all p ≤.002). Findings of racial/ethnic differences were similar among victims of mass murder committed with means other than firearms for Black, Asian, and White individuals. These findings highlight different areas of victimology within the context of these incidents. [ABSTRACT FROM AUTHOR]

Background: Mass shootings account for a small fraction of annual worldwide murders, yet disproportionately affect society and influence policy. Evidence suggesting a link between mass shootings and severe mental illness (i.e. involving psychosis) is often misrepresented, generating stigma. Thus, the actual prevalence constitutes a key public health concern. Methods: We examined global personal-cause mass murders from 1900 to 2019, amassed by review of 14 785 murders publicly described in English in print or online, and collected information regarding perpetrator, demographics, legal history, drug use and alcohol misuse, and history of symptoms of psychiatric or neurologic illness using standardized methods. We distinguished whether firearms were or were not used, and, if so, the type (non-automatic v. semi- or fully-automatic). Results: We identified 1315 mass murders, 65% of which involved firearms. Lifetime psychotic symptoms were noted among 11% of perpetrators, consistent with previous reports, including 18% of mass murderers who did not use firearms and 8% of those who did (χ2 = 28.0, p < 0.01). US-based mass shooters were more likely to have legal histories, use recreational drugs or misuse alcohol, or have histories of non-psychotic psychiatric or neurologic symptoms. US-based mass shooters with symptoms of any psychiatric or neurologic illness more frequently used semi-or fully-automatic firearms. Conclusions: These results suggest that policies aimed at preventing mass shootings by focusing on serious mental illness, characterized by psychotic symptoms, may have limited impact. Policies such as those targeting firearm access, recreational drug use and alcohol misuse, legal history, and non-psychotic psychopathology might yield more substantial results. [ABSTRACT FROM AUTHOR]