On Sunday, July 22, around 10 PM on the Danforth strip—Toronto’s bustling Greektown neighbourhood of busy restaurants and open patios—Faisal Hussain pulled a handgun and sporadically opened fire on passersby, killing a ten-year-old girl and an 18-year-old woman, and severely wounding 13 others. Shortly after, following a nearby gunfire exchange with police, Hussain was found dead. (The provincial police watchdog, the Special Investigations Unit, has not yet confirmed the details of his death, though police sources told the Toronto Star he died of a self-inflicted gunshot wound.)

The following day, Hussain’s family released a public statement expressing their condolences to anyone suffering on account of the “senseless violence” caused by their son’s “horrific actions.” “Our son had severe mental health challenges, struggling with psychosis and depression his entire life,” the statement read. A combination of therapy, medication and professional intervention were ultimately unsuccessful, the family said. “While we did our best to seek help for him throughout his life of struggle and pain, we could never imagine that this would be his devastating and destructive end.”

Since then we’ve seen a steady trickle of information about Hussain—often conflicting and citing confidential sources—throughout the media. Sources have told Global News that Hussain “was fascinated by death and explosions,” that he “also liked replica handguns,” and that he thought he was the Joker from Batman.

Regardless of Hussain’s motivation or ideology, it appears he was a deeply troubled young man. We spoke to a number of experts, including lawyers, psychiatrists and extremism researchers, about how Hussain’s mental health may, or may not, have played a role in Sunday’s shooting.

What is psychosis?

Psychosis, psychiatrists say, is a severe mental disorder in which the individual entirely loses touch with reality—they become unable to be clear of what is real and what is not. Dr. Alexander Simpson, the Chief of Forensic Psychology at Toronto’s Centre for Addiction and Mental Health (CAMH), Canada’s leading mental health hospital, says the patterns of psychosis are relative to the individual’s personal experience. “There’s a big range of severity of psychosis and there are different patterns with different people,” Dr. Simpson told VICE. Still, there are many symptoms that are particularly common among those who struggle with psychosis, he says: hearing voices and noises that aren’t there; the onset of visions and hallucinations (involving hearing, seeing, smelling, tasting), which often cause the individual to react physically; persecutory and grandiose delusions; and intense disorganization of thoughts and feelings, particularly fear.

Psychotic episodes—heightened, intensified moments of illness that demand immediate treatment—vary both in length and intensity. These episodes, which can be spurred by any number of factors (extreme stress, conflict with loved ones, major losses, trauma, poverty and low income, lack of social support), can come on gradually or suddenly: a single one can, ostensibly, persist for weeks or months. For some people, the symptoms never really go away, remaining consistent but increasing and decreasing in severity over time. The condition is treatment-responsive, but a small percentage of people are unaffected by professional help.

Are people with mental illness more likely to be violent?

Generally, there is no increased risk of violence for people with mental illness, says Dr. Simpson. But with psychotic illness, he says, there is a slight increase in the inclination toward violent behaviour. This prospective violence, though, is confined to the acute episode phases of the illness, when the symptoms are at their worst. If the individual receives immediate treatment and the episode settles down, the person is at a lower risk of violence than the general population.

“About five percent of homicides are associated with mental illness,” Simpson says. “But, the other way, 95 percent are not. Most people, even while having an acute episode, are not dangerous to other people—it’s only a small percent who are.”

Are police equipped to deal with people in mental crisis?

“When a person is experiencing mental distress, barking commands at them to drop whatever they’re doing, or to stop, or turn around, is simply ineffective,” Morgan explains, citing a recent report written by Ontario ombudsman Paul Dubé. “The evidence shows…that [police] tend to be overly aggressive and, instead of de-escalating, there’s often an escalation….Are they equipped? I don’t think they are.”

“I think there has been huge progress made in that area,” Dr. Simpson says. “But I think there’s more work to be done.”

Are mentally ill people responsible for violence?

The general rule of thumb among psychiatrists and legal professionals alike is that mental illness is not an excuse for committing violent crime so much as a complication that potentially produces violent behaviour. The same way arrhythmia is a complication of heart failure, Dr. Simpson explains, so too is violence a complication of psychosis. It is for this reason that the “not criminally responsible” verdict—formerly called “not guilty by reason of insanity”—is present in Canadian law.

“Canada’s criminal law does not give people with mental health issues a get-out-of-jail-free card,” says criminal defense lawyer Michael Spratt. “Instead we recognize that those who truly cannot appreciate the nature and consequences of their actions due to mental health issues need to be treated and supervised until they they do not pose a risk to the public.”

We’ve seen this at play recently in two of the worst mass murders in Canadian history. Matthew de Grood, who killed five of his friends during a psychotic episode and was found not criminally responsible; Alexandre Bissonnette, who gunned down six men at a Quebec City Mosque, had mental health issues but ultimately pleaded guilty to his horrific crimes.

Can mentally ill people legally obtain a gun in Canada?

The regulations Canada has in place for handguns, even for those without mental illness, are rather strict—particularly in relation to other parts of the world (i.e. America). Those who apply for a gun license in Canada are required to disclose mental health issues and to offer personal references of people who will testify to their character and temperament. Based on Hussain’s family’s description of his “severe mental health challenges,” including psychosis and depression, as well as reports that he was previously investigated by police under the Mental Health Act, one would think he might have been flagged while applying for a gun license. CTV News reported Hussain’s gun was likely illegally obtained from a “gang-related source.”

Do groups like ISIS target people with mental illness?

Early Wednesday morning, Toronto police Chief Mark Saunders refuted Daesh claims that it was responsible for Sunday’s mass shooting. Saunders said there is “no evidence” that Hussain was “a soldier of the Islamic State,” as a bulletin published to Amaq News Agency claimed this morning.

Rukmini Callimachi, a New York Times correspondent who covers ISIS, published a thread on Twitter this morning analyzing the Amaq statement. “They are essentially saying that Faisal Hussain...was self-radicalized,” she wrote. “Unfortunately we know that ISIS pushes its propaganda to people who are mentally vulnerable, and mental illness is not a barrier to being indoctrinated by them.” Callumachi concludes her thread by noting that in order to determine whether Hussain had a relationship with ISIS, we would first have to find evidence of him consuming their propaganda.

Amarnath Amarasingam, a senior research fellow at the Institute for Strategic Dialogue, explained that ISIS is likely just parroting theories they’ve seen reported in the media that link Hussain to greater terrorist motives—their claim didn’t arrive until shortly after news outlets began to report the shooter might have been radicalized. “There hasn’t been any real evidence that this guy was in contact with anybody in ISIS...so we’ll have to wait and see,” he said.

“The fact that the RCMP hasn’t taken over the investigation I think is a good indicator that there is no national security component to it.”