98% of mass public shooters are men.
Only four of the 189 mass shooters in our database were women, two of whom partnered with a male shooter.
Mass public shootings most frequently occur at places of work and commerce, but trends change over time.
The shooting location also dictates demographic trends…
Because many mass public shooters are location "insiders"…
Mass shooters have many grievances, but shootings motivated by hate and fame-seeking have increased since 2015.
However, hate comes late along the pathway to violence and so-called "motives" can become labels used to explain away the problem of mass shootings. Mental illness, for example, is not a motive. If a mass shooter has a mental health diagnosis, this doesn’t mean that their every action is related to that diagnosis or that their symptoms caused them to pull the trigger. All we can say with some degree of certainty is that no one living a fulfilled life perpetrates a mass shooting.
The mental health of mass shooters is complicated…
Around 30% of mass shooters experienced psychosis, but perpetrators were only acting on their hallucinations and delusions in 10% of cases.
Still, many mass shooters were suicidal. Mass shootings are public spectacles of violence intended as final acts.
Most mass shooters are actively suicidal. Whether they kill themselves, are killed by police, face the death penalty, or spend the rest of their lives in prison, they have no plan for what comes next. This is what makes mass shootings different from other gun crimes. It is also why traditional deterrence measures, such as armed security or harsh criminal sanctions, may do little to avert them.
And 80% of mass public shooters were in a noticable crisis* prior to their crimes:
* A crisis is a time-limited event that overwhelms someone's usual coping mechanisms. It looks different for different people, but it usually manifests in a marked change in behavior from baseline. For example, about two-thirds of mass shooters exhibited increased agitation in the run-up to their shooting.
Most mass shooters exhibited between one and four crisis signs. However, over a third of shooters showed five or more crisis signs.
Most mass shootings are committed using handguns.
However, AR-15-style assault rifles are disproportionately represented in mass shootings compared to other forms of gun violence.
A majority of firearms used in mass shootings are legally purchased and about a quarter are obtained less than one month prior to being used in a mass shooting.