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 to, and then fled, a nearby doughnut shop. He jumped 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?"
"What were you running from?"
"I don't know."
Richardson quoted Kachkar as saying at another point:
"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.
"They all said he was different," Richardson said.
Kachkar, who had travelled to Toronto from St. Catharines, Ont., in the days before Russell'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 although the doctor thought Kachkar's fear "genuine," court heard.
"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."
Richardson said the three psychiatrists who assessed him extensively — one at the prosecution's request — were "uncontradicted" in their view that Kachkar was suffering full-blown psychosis when he went on his two-hour slow-speed rampage.
"He had completely lost touch with reality," Richardson said. "This case was a tragedy, but it's not a murder."
The lawyer said the psychiatrists had rejected any suggestion Kachkar was faking his symptoms or had acted in anger, as the prosecution has maintained.
If the jury does decide he was criminally responsible, Richardson said, they should convict him of manslaughter.
"Whichever route the prosecutor is trying to get to murder here, it doesn't stick. It doesn't fly," Richardson said.
"The Crown was trying to use logic in a situation that wasn't logical."
Kachkar didn't have time to form an intent to kill the officer in the seconds that passed after Russell stopped, got out of his cruiser, fired three shots and was hit by the plow, the lawyer said.
Court also saw dash-cam video that appears to show Kachkar missing from behind the wheel one second before he hit Russell, raising the question of whether he was ducking to avoid the officer's gunfire.
Richardson noted Kachkar had not attempted to hit anyone during his rampage, and may have been trying to avoid Russell.
"We're talking inches, and that's another very sad part of this case," Richardson said.
Russell's wife Christine sat with supporters during the submission. She has said she would speak about the trial, which began Feb. 4, after it finishes.
The Crown makes its closing arguments Friday. Superior Court Justice Ian MacDonnell will then charge the jury, which is expected to start deliberations on Monday.