A man on trial for the death of Toronto police Sgt. Ryan Russell is presumed to have been behind the wheel of the snowplow that killed the officer, but jurors will have to consider what Richard Kachkar’s mental state was when the incident occurred.

Kachkar’s trial began Monday, just over two years after Russell, a veteran officer, was struck and killed by a snowplow near Avenue and Davenport roads.

The 46-year-old has pleaded not guilty to charges of first-degree murder and dangerous driving in relation to Russell’s death.

But Ontario Superior Court Justice Ian MacDonnell told jurors Monday that Kachkar was the man behind the wheel of the stolen snowplow.

"There will be no dispute that Mr. Kachkar was the person who was driving the truck," MacDonnell said. "That is, this case is not a whodunit."

Richard Kachkar is charged with first-degree murder in the death of Toronto police Sgt. Ryan Russell. (Alex Tavshunsky/CBC)

Crown attorney Christine McGoey told jurors that the dispute is over Kachkar's "state of mind." She said it will be revealed that the accused had the intent to kill Russell and that Kachkar knew he was a police officer.

The Crown alleges that Kachkar purposely drove at a police cruiser with the snowplow he was driving on the morning of Jan. 12, 2011.

When Russell got out and fired three shots at the oncoming snowplow, the Crown says that Kachkar sped up and struck the officer.

The plow knocked Russell down and fractured his skull. McGoey told jurors that Kachkar did not stop or slow down as the officer lay on the ground, unconscious and bleeding.

When paramedics were en route to help the fallen officer, McGoey said that the accused drove past them and opened the door of the truck and made reference to shots being fired, as well as to the Taliban.

McGoey said Kachkar continued to drive for another hour, hitting parked vehicles — some with people inside them — until police were able to stop him.

Jurors heard from the Crown that Kachkar ignored emergency task force instructions to leave the snowplow and instead accelerated toward one of the officers and pinned his leg between the vehicle and a garbage truck.

Another officer then shot Kachkar twice. When police pulled the accused from the vehicle, he made reference to his sister being the reason for his actions or that it was her fault.

McGoey said that Kachkar separately told paramedics and another man that he was concerned they might poison him or implant a microchip inside him, as well as "something about Russian Facebook, the government and 9/11 and said it was all a Russian video game."

Accused was in shelter hours before incident

The Crown also told jurors about the night before the deadly incident, when Kachkar had been staying at a Toronto homeless shelter.

He asked a staff member at the shelter to call the RCMP because he thought he might “do something bad.” But McGoey said he then told staff he didn’t want them to call police.

Kachkar travelled to Toronto from St. Catharines, Ont., to look for work. He was estranged from his wife and children.

After giving its opening statement, the Crown called its first witness on Monday — Daniel Da Silva, the rightful driver of the stolen snowplow.

He testified that Kachkar was barefoot and without a jacket when he rushed out of a Tim Hortons that Da Silva had just entered and took off in the truck that had been left running outside.

Kachkar's trial is expected to last about two months.

The fallen officer's widow, Christine Russell, attended the first day of the trial. (CBC)

Russell, 35, became the first Toronto police officer killed while on duty since 1994. He had been promoted to sergeant six months before his death.

His widow, Christine Russell, attended the first day of the trial in Toronto on Monday.

Outside court, she thanked the media for the support they had shown her in the wake of her husband’s death.

Russell said that seeing the accused in person was difficult for her.

"It’s not easy to sit there and sit so close to someone you know has done so much harm," she told reporters.

When Russell died, he also left behind a young son named Nolan.

Russell's funeral was attended by thousands of police officers and members of the public.

With files from The Canadian Press and reports from the CBC's Genevieve Tomney