The criminal justice system is interested in the predictive power of criminological theories as it would like to use data to identify those who would commit crimes to promote public safety. One of the areas of high interest is data and theories that would help reduce gun violence and mass public murder. The number of people in the United States who have died from gun violence is significant—more than 30,000 per year or about 92 per day. Of particular concern to the public are mass public murders, defined as the killing of four or more persons. Accurate national statistics on public mass shootings are difficult to obtain but the Congressional Research Service reports an average of 22.4 mass shootings a year from 2009 to 2013.49 Dr. James Alan Fox, criminologist at Northeastern University and coauthor of a study of mass public murders, reports that the number of mass public shootings has roughly held steady in recent decades despite public perceptions that there are more mass shootings. Dr. Fox attributes the public perception to media coverage and the availability of news accounts of shooting. One of the factors driving an interest in mass public shootings is the concern by some of the increase in gun ownership and licenses to carry a concealed gun. (About 13 million Americans are licensed to carry a concealed gun.) However, despite the increase in gun ownership, the national homicide rate has declined to its lowest level in two decades. These data make it impossible to link mass public shootings with gun ownership as there is actually an inverse correlation—as gun ownership has gone up, homicides have gone down.50
Another question researchers ask is what is the relationship between mental illness and mass public killers? While there is a public perception of a strong relationship between mental illness and mass murderers, most experts say there is no relationship. Dr. Alan Fox concludes that “most involved in family massacres are not seriously mentally ill, but vengeful.” Most experts agree that most people who are mentally ill are not violent.51
However, there are studies which have reported that more than 60% of mass public killers had a serious mental health disorder or had at least some symptoms indicating that they did have one. Contrary to popular belief that victims of mass public murder are targeted randomly, the majority of experts believe that they target specific people for specific reasons. For example, in 57% of the mass murder shootings, at least one of the victims was the shooter’s partner or family member.52
When a specific person is not targeted, the killer selects a broad category to attack such as a religious group, immigrants, women, military personnel, or racial identity. Experts posit that in cases where the persons are truly randomly targeted, suggest mental illness on part of the shooter. The profile of the public mass shooter that emerges from an analysis of several studies is that the shooter is an older (30s or 40s) white male who is single, separated, or divorced. They obtained their guns legally. They are depressed, in social isolation, and have a history of frustration. However, except those who carried out random mass killings, they are not out of touch with reality, do not hear voices, and are not suffering delusions. They admire previous mass murders seeing them as “someone who wins one for the little guy.” Many play violent video games extensively. In summary, the signs of public mass killers are anger, disappointment, and solitude.53
The problem is that this profile is not unique to the public mass murderer. Many fit this profile and are not homicidal. The profile provides little usefulness in identifying individuals who are potentially dangerous and should be targeted from treatment or law enforcement intervention.54