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LE takeaways from the largest database of life histories of U.S. mass shooters

Researchers say being part of a set of available and long-term resources to preempt active shooters is far more important than annual active shooter drills


Memorials and messages hang on a fence at the First Baptist Church of Sutherland Springs, Wednesday, Oct. 31, 2018, in Sutherland Springs, Texas, one year since a gunman opened fire on worshippers attending Sunday service at the church, killing more than two dozen people and wounding others.

AP Photo/Eric Gay

Active shooter drills in schools and harsh punishment for students who threaten violence may be counterproductive in preventing mass killings on school grounds according to a recent study by The Violence Project, a National Institute of Justice-funded analysis of U.S. mass shootings.

The research project, conducted by The Violence Project co-founders Dr. Jillian Peterson and Dr. James Densley, both faculty members at Hamline University in Minnesota, identified 171 mass public shootings from 1966 to 2019 that were coded on 99 life history variables, including mental health history, trauma, interest in past shootings and situational triggers. The study also interviewed shooting survivors, including shooters. The authors do not name any killers in the study in an intentional “no notoriety” commitment.

The study was not limited to mass killings at schools and universities. “The most common mass shootings are in workplaces (28.1%), followed by restaurants/bars/nightclubs (14%), retail establishments (12.9%), houses of worship (6.4%), K-12 Schools (7.6%), colleges/universities (5.3%), government buildings/places of civic importance (2.9%). 22.8% are in other public spaces, like neighborhoods and campsites,” the researchers wrote.

Findings consistent with other studies

This study confirms that there is no reliable template for matching a profile to a potential shooter, and no universal definition of the term although the study references the FBI standard of four deaths in a single event as a “mass murder.”

Mass shootings are not new but are increasing in lethality and frequency. Sixteen of the 20 most deadly mass shootings in modern history occurred in the last 20 years, eight of them in the last five years. The magnitude of fear that these events generate is significant because of the symbolic loss of safety in places normally considered safe for routine life activities.

The researchers also suggest that, since most firearms used in mass shootings are handguns that are either legally obtained or stolen, there is little evidence that most proposed gun control measures would be effective in preventing mass killings.

The statistical probability that the shooter is male and Caucasian remains intact across all mass killings but does vary depending on the site and target. Mass killing events remain rare, comprising fewer than 1% of all firearms homicides and rarer than lightning strikes as a cause of death.

Experts also agree that mental illness is not significantly over-represented among mass killers and that no single diagnosis before or after the attack is common to all shooters.

Fresh findings

The study shows a contrast in the demographics and dynamics of mass killings. Shooters in workplaces, college campuses and K-12 properties vary. That means that response planners may find that a single template for all mass shooting incidents is inadequate, especially when many other mass casualty events excluded from this study such as non-firearm attacks, domestic violence mass shootings where fewer than half of the victims are non-relatives killed, and mass shootings attributable to underlying criminal activity.

Aggregate data reveal that the K-12 school shooter is typically a white male student of the school with a history of trauma who is suicidal. He leaks his plans ahead of time, engages in a high degree of planning and has an interest in guns. He uses multiple guns that he stole from a family member.

The college and university shooter is likely a non-white male current student with a history of violence and childhood trauma who is suicidal. He uses handguns that he legally obtained and leaves something behind to be found (like a video or “manifesto”).

The workplace shooter tends to be a male in his 40s, no racial profile, but is an employee of the blue-collar shooting site and having trouble at work. He uses handguns and rifles that he legally owns.

The house of worship shooter is a white male in his 40s who is suicidal with a prior criminal record and violent history. He uses a handgun in a Christian church where he knows victims. He shows a low degree of planning, motivated by domestic spillage and hate.

Moving from “profiles” to “pathways”

Drs. Peters and Densely use the “routine activities theory” of crime to prescribe responses to threats of mass killing. This theory explains criminal choices as opportunistic when a motivated offender is aware of a suitable target vulnerable in the absence of suitable guardians. Safety practitioners have attempted to address target vulnerability and guardianship with hardware and personnel, but the researchers suggest that addressing the motivated offender may be most effective, especially in school shootings.

While target hardening and increased security staffing would be most helpful in mitigating or preventing attacks in the workplace and public area shootings, the reality that most school shootings are from within the target population provides an opportunity for intervention. Perhaps the most controversial aspect of the report’s recommendation is that the current practice of active shooter drills and harsh punitive responses to threats communicated by students may be counterproductive.

New thinking on prevention

Rather than trusting in profiles, Dr. Peters recommends the pathway approach in preventing school mass shootings. She postulates that since school shooters are almost always current or former students, repeated active shooter drills can actually provide a blueprint for a shooting that is well-rehearsed and normalized, as well as traumatic for students and staff.

Since nearly 80% of shooters have given some indication of their plans via social media or making some sort of outcry to a peer or adult before the event, there is a potential for early intervention. Currently, this intervention includes likely expulsion and criminal prosecution. Peters suggests that this response can increase the potential for that student to attack by adding to their motivation. In the alternative, she recommends swift intervention with supportive resources and ongoing supervision and care.

Police priorities

Citizens expect the police to be experts with regard to violence prevention, especially school violence. We owe them to be aware of valid research to answer their questions. When school administrators ask local law enforcement for counsel on active shooter drills and threats of violence, a close look at this report will inform us that being part of a set of available and long-term resources to pre-empt active shooters is far more important than an annual drill.

Joel Shults operates Street Smart Training and is the founder of the National Center for Police Advocacy. He retired as Chief of Police in Colorado. Over his 30-year career in uniformed law enforcement and criminal justice education, Joel served in a variety of roles: academy instructor, police chaplain, deputy coroner, investigator, community relations officer, college professor and police chief, among others. Shults earned his doctorate in Educational Leadership and Policy Analysis from the University of Missouri, with a graduate degree in Public Services Administration and a bachelor degree in Criminal Justice Administration from the University of Central Missouri. In addition to service with the U.S. Army military police and CID, Shults has done observational studies with over 50 police agencies across the country. He has served on a number of advisory and advocacy boards, including the Colorado POST curriculum committee, as a subject matter expert.

His latest book The Badge and the Brain is available at
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