Social network analysis as a tool for understanding mass shooting prevention: A case study of the Marjory Stoneman Douglas High School shooting

This study presents a social network analysis of the pre-incident social and behavioral environment surrounding the perpetrator of the 2018 shooting at Marjory Stoneman Douglas (MSD) High School in Parkland, Florida. Social network analysis is a valuable tool for visualizing and understanding social ties and relations among entities and has been applied across social science disciplines to study deviant and legitimate social groups. We developed an ego network for the MSD perpetrator to understand who comprised his social network and the warning signs these network members both observed and reported. Results indicate that nearly all network members observed at least one type of concerning behavior, but only about half reported them to authorities. Gun-related behaviors and physical aggression and violence were predominantly observed. The network itself was sparse and had little cohesion, and influential actors within the network may have restricted the flow of information rather than facilitated its sharing. These findings suggest several directions for future research aimed at preventative policy, including development of centralized reporting systems, specialized awareness training for families, students, and teachers, and continued exploration of the egocentric social networks of mass public shooters and plotters to uncover the attributes of successfully prevented cases. • First application of egocentric social network analysis to mass public shootings. • Examines MSD shooter's social environment prior to the shooting. • All known network members observed warning signs, few reported. • Sparse and fragmented social network restricted information flow to authorities. • Network members held key pieces of information; lacked cohesion/resources to report.