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

Abstract

This study compares foiled and completed mass shootings involving leakage (2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015)(2016)(2017)(2018)(2019) to determine the factors associated with leakage, modes of leakage, and bystanders encountering leakage that contributed to preventing mass shootings. Findings indicate offenders who engaged in leakage were more likely to be foiled when they were younger (<18 years old), intended to target education locations, worked with co-offenders, and leaked information exclusively online. While not statistically significant, a higher proportion of mass shootings were also foiled after offenders leaked information to friends and classmates. Alternatively, offenders who engaged in leakage were more likely to complete their attack when they were middle-aged (35-44 years old); targeted commerce and workplace locations; leaked information via in-person communication and written statements; and leaked information to family members, wives/girlfriends, and coworkers. A discussion of findings illustrates the successes and failures in leakage-based prevention, as well as avenues for advancement in leakage identification and reporting. Public Significance StatementLeakage is the communication of violent intent that sometimes precedes an act of extreme violence. Given the prevalence of leakage among mass shooters, it is important to understand the types of leakage that mass shooters display before they attack, as well as how they communicate this leakage, and to whom. This study examined foiled mass shooting plots and completed mass shooting incidents and found that foiled mass shootings were more likely to involve young students targeting their schools and engaging in online leakage, while completed mass shootings involved adults targeting commerce or workplace locations, who verbally leaked their plans to family, intimate partners, or coworkers.