A Sequence Analysis of the Behaviors and Experiences of the Deadliest Public Mass Shooters

Abstract

Researchers of public mass shooters are increasingly focusing on the pre-attack behaviors and experiences of these offenders. Varying in scope from consideration of individual factors to more generalized life course and threat assessment analyses, their scholarship has identified behavioral and experiential factors associated with public mass shooters. However, what is generally missing from this body of research is consideration of the order in which the offender encounters these factors, and prior related research has shown that analyzing sequences allows for insights not available from a catalogue of common characteristics. To address this shortcoming, we use a sample of offenders from 1999 to 2020 for whom the most detailed data is available and conduct a sequence analysis of their stressors, antisocial behaviors, mental health issues, and planning and preparation activities. We calculate proximity coefficients for each variable in relation to all others, capturing both local and distant connections between and among them. Our findings reveal relatively coherent phases in the lives of attackers, highlight the centrality of family problems and interest in past mass killings in the overall sequence, and provide new context to understanding the effect of mental health issues and firearms acquisition in the lives of offenders. A discussion of findings illustrates potential intervention points that may have been overlooked, as well suggestions for future research.

The Virginia Beach municipal center mass shooting: A retrospective threat assessment using the WAVR-21.

“…While it might be easy to assume that mass shooters’ lives steadily deteriorate until the point when they attack—when they have reached “rock bottom”—it is also possible that they had other very low or very high moments on an inconsistent pathway to violence. There have only been a few studies that even accounted for changes in mass shooters’ lives over time (Lankford & Silva, 2021; Silver & Silva, 2022; White, 2017), so far more research in this area is needed.…”

Current Knowledge on Potential Determinants of Mass Public Shooting Perpetration and Casualties: A Systematic Review

“…Domestic violence was also associated with lethality of mass shootings. Considering that mental health problems are associated with family/relationship issues (Silver & Silva, 2022), and that family/relationship issues can lead to mental health problems (Gibb et al, 2011), it is not possible to ascertain whether a variable was a risk factor or the pathway variable between another risk factor and the outcomes.…”

Assessing leakage-based mass shooting prevention: A comparison of foiled and completed attacks.

“…For completed mass shootings, The Violence Project data set already included variables examining “leakage” and whether the leakage was “specific” (i.e., threatened shooting) or “nonspecific” (i.e., threatened violence). These cases were then verified using three other sources providing examinations of mass shooter leakage (Lankford et al, 2019; Meloy & O’Toole, 2011; Silver & Silva, 2022). These sources identified six additional cases with leakage that were overlooked in The Violence Project data.…”

“…Studies have found leakage commonly occurs prior to completed attacks (Lankford et al, 2019; Peterson et al, 2021; Silver & Silva, 2022). In other words, many completed mass shootings could have been prevented based on information known about offenders in advance.…”