TORONTO -- A barefoot man who killed a police officer with a stolen snowplow after a bizarre rampage through the streets two years ago had clearly lost his grip on reality, his first-degree murder trial heard Thursday.

In closing submissions, defence lawyer Bob Richardson said Richard Kachkar could not be held criminally responsible given his delusional state.

"He lacked capacity to form criminal intent," Richardson told the jury.

"He wasn't operating in our world."

Dressed in light dress pants and shirt under a dark blazer, Kachkar, 46, listened impassively as his lawyer reprised the evidence of three psychiatrists, who concluded he was psychotic when he struck and left a dying Sgt. Ryan Russell, 35, bleeding in the snow.

Richardson reminded jurors how a shoeless Kachkar had bolted from a downtown shelter out into the snow on the early morning of Jan. 12, 2011.

"Whatever slim hold Mr. Kachkar may have had on reality, slips away," Richardson said.

"His psychotic beliefs are driving his behaviour."

Kachkar went into and then fled a nearby doughnut shop, jumping into the idling snowplow. He drove erratically through the streets, making frequent U-turns, hitting cars and yelling about Chinese technology, the Taliban and microchips in his body.

"I don't remember. I was chased everywhere," Kachkar would later tell a police investigator.

"Where were you going?"

"Just running."

"What were you running from?"

"I don't know."

Richardson quoted Kachkar at another point as saying:

"I don't know what happened. It was like a dream or something. A normal person wouldn't do that. I don't know what's going on."

In fact, the lawyer told jurors, Kachkar had shown signs of a major mental disorder for years, a situation that became increasingly obvious in 2006 after his father died.

Several people who had contact with him in those years were concerned about his mental health.

He exhibited "tangential thinking," frequently going off topic and making it impossible to have a proper conversation with him.

One person talked about how Kachkar spent hours spinning a combination lock at a shelter in St. Catharines, Ont., where he lived.

"They all said he was different," Richardson said of those who knew the accused.

Kachkar, who had travelled to Toronto from St. Catharines in the days before Ryan's death, told one man in a hushed voice there were cameras all around, Richardson said.

On the day before Russell died, Kachkar went to a clinic, and said he was "scared," but couldn't say why, court heard, but the doctor thought Kachkar's fear "genuine."

"Kachkar appeared panicked, crazed, scared," his arresting officer has testified.

"My sister made me do it," Kachkar told police. "This is my sister's fault."

"When he had completely lost touch with reality, he tragically struck and killed Sgt. Russell," Richardson said.

"This case was a tragedy, but it's not a murder."

Richardson said the three psychiatrists who assessed him extensively were "uncontradicted" in their view that Kachkar was suffering from full-blown psychosis when he went on his two-hour slow-speed rampage.

The doctors also rejected any suggestion Kachkar was faking his psychotic symptoms, or was merely acting out in anger as the prosecution has maintained.

"The Crown was trying to use logic in a situation that wasn't logical," Richardson said.

If the jury decides he was criminally responsible, Richardson said, they should then return a verdict of manslaughter.

Russell's wife Christine sat with supporters during the submissions. She has said she would speak candidly about the trial, which began Feb. 4, after it finishes.

The Crown has yet to make closing arguments before Superior Court Justice Ian MacDonnell charges the jury.