Why mass murderers may not be very different from you or me

It’s reasonable to think that anyone who guns down 22 human beings in cold blood must be deranged or de facto have a mental illness. But the truth about mass killers and the link to mental health is more complicated than that.

One of the largest studies of mass killers, conducted by Dr. Michael Stone and involving 350 people, found that only 20 per cent had a psychotic illness; the other 80 per cent had no diagnosable mental illness — just the everyday stress, anger, jealousy and unhappiness the rest of us have.

Likewise, an FBI study of active shooters between 2000 and 2013 found that only 25 per cent had ever received a psychiatric diagnosis and just 5 per cent had a psychotic illness.

(Some of my psychiatric colleagues like to point out that mass killers commonly have histories of physical and sexual abuse. Sure, but given the prevalence of such abuse in America, it seems obvious that a vast majority of traumatised people do not turn into mass killers.)

Still, the clear implication of these findings is that people in the grip of ordinary emotion are capable of carrying out heinous acts of violence; you don’t need to have a mental illness to be a “monster.”

We can’t know for sure whether the suspect in the El Paso killings, Patrick Crusius, was mentally ill without detailed knowledge of his personal and medical history. But his online writing suggests we should not be so fast to assume that he is.

In a manifesto attributed to him, Crusius railed against immigration, described a plan to separate America into racially distinct areas and warned that white people were being replaced by foreigners. He said that “this attack is a response to the Hispanic invasion of Texas.”

To me, the statement appeared logical, coherent and not particularly rambling or delusional. Strikingly, the manifesto seemed to echo what Trump has been saying all along about immigrants. For example, at a recent Florida rally the president said, “You look at what is marching up, that is an invasion!”

Seen from this perspective, it is entirely plausible that the El Paso killer is a rational person who happens to be inspired by a hateful racist ideology.

The scary truth is that ordinary human hatred and aggression are far more dangerous than any psychiatric illness. Just think of the many people driven to mass murder because they were fired by employers or dumped by girlfriends. In all likelihood, they were not mentally ill but simply full of rage — and well armed.

In fact, mental illness contributes to about 3 per cent of violent crime in America. The best evidence shows that there is a very small increase in the risk of violence only for those with serious mental disorders like bipolar disorder and schizophrenia.

The notion that we can identify mass killers before they act is, as yet, an epidemiologic fiction. These individuals typically avoid contact with the mental health care system. Even if they didn’t, experienced psychiatrists fare no better than a roll of the dice at predicting violence.

Other mass killers bear this out. Brendon Tarrant, who murdered 51 people last March in a mosque in Christchurch, New Zealand, was found at trial not to be mentally ill. Rather, he was a white supremacist who planned his carnage for two years and was driven by an anti-immigrant and racist ideology similar to Crusius’s. And like Crusius, he believed in a white supremacist conspiracy theory called “the great replacement,” which posits that white Europeans, with the complicity of “elites,” are being replaced by non-European people through mass immigration.

Then there is Dylan Roof, who murdered nine people in 2015 in a church in Charleston, South Carolina. He too espoused racial hatred in an online manifesto. Though he was given a diagnosis of social anxiety disorder and mild autism by an evaluating psychiatrist, neither of these diagnoses involved a state of psychosis that might have rendered him unable to comprehend the nature of his actions.

Judging from their manifestoes, you have to wonder whether, at the very least, these killers expected social approval from those who shared their racist ideology, to say nothing of a desire for fame.

Given the global resurgence of white nationalism and xenophobia in recent years, is it really surprising that a few individuals have responded to this climate of hate by violently channelling such ideas? After all, we are social animals who are easily swayed by our environment. And that environment is awash in rage these days.

What this suggests is that bolstering mental health programmes — while a worthy goal — will not solve our mass shootings epidemic. More effective policies might involve gun control, including enhancing background checks and expanding so-called extreme risk protection orders, which would allow law enforcement to temporarily remove firearms from people deemed potentially violent.

This should scare the hell out of all of us. The next mass killer is out there — somewhere — watching very carefully what we say and do to one another. And he may be as sane as you or me.

Richard A. Friedman is a professor of clinical psychiatry and the director of the psychopharmacology clinic at the Weill Cornell Medical College