HALIFAX - The mother of a mentally ill Nova Scotia man facing two murder charges says her son turned to violence because his mind was overwhelmed by a "monster" he could no longer keep at bay.

Donna Race, speaking out for the first time about her son Glen's 10-year battle with schizophrenia, told a news conference Wednesday she tried to have him treated involuntarily in 2007, but police and health officials said there was nothing they could do.

"He had become so psychotic that his monster overpowered him," she said in an even voice, her husband Mark and other son Doug sitting beside her.

"He wasn't able to fight anymore."

The Halifax-area woman said she was told her troubled son -- now 29 -- couldn't be sent to a psychiatric facility without his consent unless he posed a danger to himself or others.

Convicted in 2008 of fatally shooting Darcy Manor in Mooers, N.Y., Glen Race now faces murder charges in the deaths of two Nova Scotians, Michael Knott and Trevor Brewster.

Knott's body was found on a path in southwestern Nova Scotia on May 5, 2007, and Brewster's body was found four days later under a boardwalk at a Halifax lake.

Race is already serving a life sentence for the Manor murder on May 10, 2007. He was extradited from the United States in October.

On Wednesday, the young man's mother said he was a well-adjusted second-year university student in 2001 when he started to withdraw from his family and friends, lost weight and started engaging in increasing unusual behaviour, such as spending a week in the woods on his own.

She said he was quickly diagnosed, but she witnessed a great deal of bizarre behaviour over the next six years because he would stop taking his medication.

"To have him at the point where he would hurt somebody, like he has, we never would have thought that," she said.

However, she confirmed that the family warned police and doctors about her son's erratic behaviour in the week before the killings. But she said nothing was done.

She noted that it wasn't until after her son had spiralled out of control that the Nova Scotia government passed the Involuntary Psychiatric Treatment Act, which could have been used to detain him for treatment.

"I believe more should have done to contain him," she said. "The biggest fear I ever had was losing my son. And I did lose him, through his mental illness and through the crimes."

Doug Race said his brother's battle with schizophrenia was tough on the family.

"Insane becomes the new normal in your household."

Still, Doug Race said the province's mental health system did what it could to help a man who refused treatment.

Race's father told the news conference that his son will plead not guilty on both murder charges because he wasn't criminally responsible for his actions while in a psychotic state.

As well, the parents said they want their son to stay in Canada after his Halifax-area trial, even though U.S. authorities expect him to return to an American prison to complete his sentence for the Manor murder.

"We would love that, for sure," Mark Race said. "He's a Canadian citizen. It will come out that he wasn't sane at that particular time."

The family's lawyer, Joel Pink, confirmed he is considering a constitutional challenge aimed at keeping Glen Race in Canada. But he admitted such a move would be a long shot, saying he is consulting with legal experts in Ontario.

Pink said if the constitutional challenge falls through, the family will consider appealing the U.S. conviction.

Doug Race, who started the news conference by offering condolences to the victims' families, said it was unfortunate that public attention is focused on mental illness only when extreme cases make the news.

"When treated, when the delusions are controlled ... it's almost nil for any type of violent acts," he said, adding that increased public awareness is key to eliminating the stigma associated with mental illness.

He and his father said the Nova Scotia government must invest more on mental health treatment.

"We typically sweep mental health under the rug," he said. "It's what we've been doing for years and years. Nothing has been solidly done so far."

The family said Glen Race is now taking medication that is helping him cope with his illness.

"He looks good," his mother said. "He doesn't look like the Glen who committed these crimes."

Stephen Ayer, executive director of the Schizophrenia Society of Nova Scotia, said the disturbing case reveals what many families go through when a loved one becomes mentally ill.

"In this case, the result was horrific for four families," he said. "This family has struggled with that. Their choice was to try to get involuntary treatment and they found they were unable to do that."

Glen Race is to return to a Halifax-area court April 21. A date for his latest trial has yet to be set.