Identifying consistent patterns among perpetrators of mass murders in academic settings, particularly by firearms, is critical for prevention efforts. Severe mental illness (SMI) is a hypothesized risk factor that has not been reliably predictive. A recent study compared mass shootings with mass murders by means other than firearms occurring in schools, colleges, and universities, while examining the relationship between SMI and mass murders in these settings. Mass murder was defined as three or more individuals killed in one event, without a cooling-off period, while SMI was defined as psychosis. Data from the Columbia Mass Murder Database (CMMD) indicated that 82 (4.75%) of 1,725 mass murders from 1900 to 2019 involved academic settings. Within the United States, 63.2% of mass murders in academic settings involved firearms. The majority of mass shootings (59.6%) involved at least one semi- or fully automatic firearm.

The largest percentage of mass shooters were White (66.7%) and 100% were men, which is consistent with previous reports. Nonfirearm murders were most commonly committed by Asians/Pacific Islanders (68.0%). Furthermore, nonfirearm mass murderers were significantly older (34.1 years, SD=11.4) than mass shooters (25.5 years, SD=10.0, p=0.001). Mass shooters in academic settings were younger than mass shooters overall (32.5 years), consistent with the notion that mass shooters in academic settings are often students or recent students. In both firearm and nonfirearm groups, there was a significant number of perpetrators who died by suicide at the murder scene (32.0% nonfirearm users and 45.6% firearm users), suggesting that they may have seen their actions as a sort of final act. Notably, the majority (76.8%) of all perpetrators had no recorded history of psychotic symptoms (68.0% of nonfirearm users and 80.7% of firearm users). Less than half (47.4%) of mass shooters and 20.0% of nonfirearm users had nonpsychotic psychiatric or neurologic symptoms. See Table 1 for summary of the characteristics of mass shooters.

Overall, this study finds that mass school murders are largely perpetrated by individuals without a history of psychotic symptoms (i.e., SMI); perpetrator gender, race, and age are more consistent, albeit nonspecific, risk factors. The frequent use of semi- and fully automatic weapons and the presence of nonpsychotic psychiatric or neurologic symptoms, as well as suicide among perpetrators may have important implications for policymakers and law enforcement response in schools, colleges, and universities.

Reference:

Girgis RR et al. J Forensic Sci 2022; Epub ahead of print. Abstract.