Mass Shooters (1966 - 2019)

Since 1966, there have been 167 mass shootings in the United States, defined by the Congressional Research Service as “a multiple homicide incident in which four or more victims are murdered with firearms — not including the offender(s) — within one event, and at least some of the murders occurred in a public location or locations in close geographical proximity (e.g., a workplace, school, restaurant, or other public settings), and the murders are not attributable to any other underlying criminal activity or commonplace circumstance (armed robbery, criminal competition, insurance fraud, argument, or romantic triangle).”

Put in perspective, mass shootings are statistically rare, accounting for fewer than 1% of all firearm homicides in the United States. But they are occurring regularly in a growing number of venues, leaving a trail of mass destruction that emotionally outweighs their numbers.

According to The Violence Project, nearly all mass shooters have four things in common:

Early childhood trauma and exposure to violence at a young age

An identifiable grievance or crisis point

Have studied the actions of past shooters and seek validation for their methods and motives

The means to carry out an attack

Number of shooters by age Years old

The average age for a mass shooter was 34 years old. The youngest was 11 years old, and the oldest was 70.













Where mass shooters killed

The past decade has seen an increase in mass shootings in a variety of settings. This troubling trend has prompted a debate among proprietors, school administrators and religious leaders about the need to balance openness and inclusiveness with physical security measures.

Number of mass shootings by location

Current or former workplaces of perpetrators were the most common sites for mass shootings. Most of the shooters had been fired. Densley said a prevention strategy for businesses could include ways for managers to intervene with employees before a tragedy occurs.

Almost all of mass shooters at restaurants, bars and retail establishments were strangers to those businesses, while perpetrators in workplaces, houses of worship, and schools and colleges tended to be current or former students and insiders known to the victims.

Densley believes shielding students with bulletproof backpacks and guiding them through lockdown drills, though useful, could also prove ineffectual when nearly all K-12, and college and university shooters are insiders, and likely familiar with the layout of a building and current safety policy.

Multiple profiles

A one-size-fits-all profile of a mass shooter is nonexistent.

Mass shooters have several profiles, unique to where a shooting occurred.

In houses of worship, the perpetrator most often was a white male in his 40s motivated by domestic issues or hate. He had a criminal record and a history of violence, and used handguns or assault rifles he legally owned.

In schools K-12, the mass shooter was a suicidal white male student of the school with a history of trauma. He leaked his premeditated plan before the shooting, and most often used multiple guns stolen from a family member.

By contrast, the typical shooter at a college or university was a suicidal, non-white male student of the institution with a history of childhood trauma. He used handguns legally obtained, and left a video or manifesto detailing his intent.

Densley suggests prevention plans for all of these types of shooters should include domestic violence programs, the disruption of online hate groups and Extreme Risk Protection Orders, also known as red flag laws. Under these laws, police and family members can petition courts to temporarily remove weapons from people who may present a danger to themselves and others.

Female shooters

Of the 171 mass shooters studied, only three were women. In one case, the woman acted in partnership with a man.

While the difference in numbers between female and male mass shooters is stark, it was represented in all U.S. homicides in which 80% to 90% of offenders in a given year were men.

There are few statistics on female perpetrators of homicide, but those that are available help to explain why women tend not to commit mass shootings.

According to a U.S. Justice Department report that looked at U.S. homicide trends from 1980 to 2008, women who committed murder almost always killed someone they know, and 58% of the time, they killed a significant other or immediate family member, compared to only 18% for male killers. Women committed just 6% of all murders with multiple victims.

The circumstances and means of killing also differed between men and women. Drug- and gang-related killings tended to be committed by men. When women killed, they were less likely to use firearms and more likely to use other means, such as poison or arson, the report said.

Childhood trauma

Thirty-nine percent of mass shooters experienced early childhood trauma and exposure to violence at a young age. This includes at least one of the following: physical or sexual abuse, neglect, witnessing domestic violence in the household, having a parent who committed suicide or being the victim of bullying.

Multiple studies, including one published in the Journal of American Medical Association in 2018 found a link between childhood trauma and social, mental and physical problems in adults. Those who have experienced trauma as children were more likely to face a host of difficulties as adults, including having violent relationships, becoming dependent on drugs or alcohol, having a psychiatric disorder and becoming depressed or suicidal.

Research also shows that the more incidents of trauma a child experiences, the greater the possibility for mental or physical problems to arise in adulthood.

Peterson, who began her career as a special investigator in New York City researching the psychosocial life of death row inmates for their sentencing hearings, discovered that many of the inmates had experienced trauma. She developed a saying in the office: “The worse the crime, the worse the story.”

Mental illness

Two-thirds of mass shooters had a history of mental health concerns, which is higher than the 50% of people in the general population who will satisfy criteria for a mental illness at some point in their lives.

Twenty-three percent had a mood disorder, which includes depression or bipolar disorder. This number was also consistent with lifetime prevalence rates among the general population.

Twenty-six percent had a thought disorder, which includes schizophrenia and psychosis, and was significantly higher than the general population.

Twenty-one percent of mass shooters were on psychiatric medication.

The commonality of mental illness between mass shooters is striking, leading some people, including President Donald Trump, to argue that mental illness should be targeted as the main cause of mass shootings.

Densley urged caution in drawing such conclusions.

“Even if you have a mental illness, it doesn’t mean that the mental illness is driving the behavior,” he said. “People with mental illness may also experience living in poverty. They may also experience discrimination. They may also have a whole host of other things going on in their lives, which step-by-step may be contributing to whatever outcome comes next.”

Signs of crisis

Before they carried out their crimes, more than 80% of mass shooters were in crisis, described by The Violence Project as a marked change in behavior that is noticeable to others. Such behavior includes exaggerated emotional responses, an increased interest in violence and signs of hopelessness.

Densley said in many cases, several people had concerns about a mass shooter’s behavior, but those pieces of information were often not connected.

“You have a school teacher that notices something. You have a friend that notices something, a family member, a law enforcement member. But if those individuals are not talking to each other, that information will never get passed on, and no one will ever know,” he said.

Sixty-eight percent of mass shooters were suicidal either before or at the time of the shooting.

Densley said a shooter’s anger is channeled inward and outward.

“Outward is where the homicide comes into play, because they are angry at a certain group of people or they are wanting to put on a show as their last act. But there is also a lot of inward hatred and frustration and confusion, and that is where the suicide comes into play,” he said.

He suggested adressing elements of a mass shooting similarly to how society addresses suicide. In terms of prevention, “it changes the way in which we see these events,” he said.

Immigrant

Fifteen percent of mass shooters were immigrants. But immigrant shooters were more frequent on college and university campuses, where 5% of mass shootings took place.

The Virginia Tech mass shooting in 2007, so far the third-deadliest mass shooting in modern U.S. history, was carried out by a Korean American immigrant suffering from severe depression.

Densely noted possible underlying grievances and motivations in carrying out such a crime at one’s own school.

“It may well be that non-white immigrants feel very disconnected from university life. They may be suffering from racism or exclusion, may feel alienated. And these, we know, are risk factors for these types of shootings. Beyond it is just the race,” he said.