TORONTO -- A Toronto senior accused of murdering a fellow resident in a long-term care home and injuring another was deemed a "chronic risk" to his frail colleagues a year before a deadly attack at the facility, a psychiatrist told his trial on Thursday.

Peter Brooks has pleaded not guilty to the first-degree murder of 72-year-old Jocelyn Dickson and the attempted murder of 91-year-old Lourdes Missier.

Crown prosecutors have told jurors that late one night in March 2013, the now 72-year-old Brooks used his cane to attack Dickson and Missier in their beds at the Wexford Residence in Toronto's east end.

The jury has heard that Brooks allegedly swung his cane at Missier's head first, but the woman, who was awake at the time, raised her hands to protect herself and screamed, attracting the attention of staff who rushed in. She was left with fractured fingers, bruises and lacerations on her face, the Crown has said.

While staff were responding to what had happened to Missier, Brooks quietly made his way to another floor, where Dickson, a woman who was paralysed on one side of her body, was asleep in her bad, the Crown said.

Using his cane once more, Brooks delivered at least seven distinct blows to Dickson's head causing "massive" injuries that led to the woman's death, the Crown has said. The force of the blows was strong enough to break off the top of Brooks' cane, prosecutors said.

But even before the incidents that took place that night, "bad relationships and bad feelings" existed between Brooks and certain residents at the facility, the jury has heard.

On Thursday, Dr. Stephen Barsky, an expert in geriatric psychiatry, told the trial he assessed Brooks in April 2012 after receiving reports of three incidents of aggression by the man against other residents at the home.

"He was somewhat irritable, he was a bit sarcastic, he wasn't fully co-operative, which made the interview process somewhat difficult," Barsky said of his time with Brooks. "I did have concerns about his level of judgment."

Brooks appeared "disinhibited" and blamed the victims of his acts of aggression, saying they had annoyed him in some way before he took an action "in excess of what would certainly be warranted," Barsky said.

"I felt that he might present a chronic risk to prey on residents within a facility," he said, noting that he didn't think Brooks had been an imminent risk at the time."

"I felt Mr. Brooks would be a better candidate for placement elsewhere, such as in a psychiatric group home where there might not be other frail elderly people he could prey on."

Barsky concluded in 2012 that Brooks had probable mild alcoholic dementia and a potential long-standing personality disorder, the trial heard.

But, Barsky said, Brooks was able to appreciate the difference between right and wrong and could understand the nature and quality of his actions.

The trial has heard that on the night he attacked Missier and Dickson, Brooks then tried to make his way to the room of another woman he had a rocky relationship with but was stopped by staff who, only after a violent struggle, were able to wrestle away his cane.

When one of those staff members, a janitor, asked Brooks why he had done what he had done, the senior said it was for "revenge," the Crown has told the jury.

When police arrived at the home in the aftermath of the attacks, the officer who arrested an actively resisting Brooks said he heard a personal support worker ask the senior if he remembered what he had done to Dickson.

"Mr. Brooks responded 'I hit her with my cane,"' Const. Nick Cheung recalled for the trial, adding that he also asked Brooks about some dried blood on his hand. "(Brooks said) 'that's my blood, I broke my stick when I hit her."'