The deadly Moncton, N.B., shootings of three RCMP officers and wounding of two others illustrate the challenges faced by parents who fear their children could pose a danger to themselves or the public.

“When the police get a call that ‘my kid is acting weird,’ and uniform officers go and they look for the signals ... the only way somebody can be detained … and taken to a hospital is if they are a danger to themselves or a danger to others,” said private investigator Mark Mendelson, a retired Toronto homicide detective.

Every province has mental health legislation that allows police to detain individuals who are believed to pose a risk. Those individuals are then taken to a psychiatric facility where they can be confined for various periods of time so they can be assessed and treated.

But obtaining enough proof that an individual is a threat and should be detained can be difficult.

“It has to be exhibited. The cops pretty much have to see something. The guy’s got to say, 'As soon as you guys leave I’m taking a gun and blowing my head off', or 'I’m jumping off the balcony,' or 'As soon you leave I’m going to strangle my mother.'

"It’s only then that they can take the person in."

If the individual is assessed and released, parents may be able to go to a justice of the peace to get an order to force their family member back into the hospital. But Mendelson said that's rarely done, as it's difficult to show evidence of risk.

The father of Moncton shooting suspect Justin Bourque told the National Post that he and his wife had tried to get help for their son from police, but were told “they couldn’t do anything about it and that their hands were tied.”

Parents of California shooter alerted police

Meanwhile, in the U.S., Santa Barbara County Sheriff's deputies are under scrutiny after it was revealed they interviewed Elliot Rodger in April before he went on his shooting rampage. Police, who had been contacted after Rodger's mother expressed concerns over some of her son's YouTube videos, concluded that Rodger posed no risk.

Mendelson said that police are expected to make some really quick assessments.

"They come to a house, they don’t know this family, they don’t know these people, they don’t know the neighbours, they don’t know the history and they don’t know the kid. So they have to make these quick assessments."

They can be right or wrong, Mendelson said, but "I think generally speaking they’re pretty good at sort of looking for the clues as to, 'Is this person a candidate to be taken to the hospital?'"

'It can be very difficult'

Although it's unknown what Bourque's parents told authorities about their son, Mendelson said the suspect's Facebook page, which featured a series of posts about gun rights, revealed nothing that could have been used to detain him.

“It can be very difficult," said Anthony Moustacalis, president of the Criminal Lawyers' Association. "If the person does not have a history of being a danger to themselves or other people, or if they don’t present at the time of being a danger to themselves or other people, mental health professionals are reluctant to intervene."

"Ultimately we live in a society that quite rightly values civil liberties, and that means you don't take someone’s liberty away, even if they’re not well mentally, unless you have a proper legal basis. And where we’ve drawn the line is they have to be a threat to themselves or someone else."

Persistence in alerting the authorities is key, Moustacalis said, but he added that it can be difficult to find someone with enough experience to deal with these incidents.

"I had a situation of someone in a lot of distress. And if you asked them the basic questions — are you in fear, do you want to kill yourself or someone else — they said no.

"But I had a police officer who was experienced speak with them. The officer said, 'Well if the person who was putting the voices in your head were here, what would you do? [And he said] 'Oh I’d have to kill them.' So sometimes probing will do."

Released hours later

Mendelson said that during his experience as a police officer, there were numerous times they would take people in for assessment only for them to be released hours later.

"The hospital would say, 'Well, we talked to him, there’s no history of mental illness, he says he’s pretty good, he was just kidding, he was just looking for effect and drama.'"

Dr. Kulwant Riar, a forensic psychiatrist and clinical professor at the University of British Columbia's department of psychiatry, agreed that it can be difficult recognizing a disorder.

“They have lucid intervals and when you see them they come across as normal. The moment they leave you, that’s when the problem comes," he said.

Mendelson said it all comes down to balancing people's rights against the safety of the community.

"Should you be detaining people and having them assessed based on things you think they might do as opposed to things they’re doing currently or have done in the past? And that’s a very very difficult line."