TORONTO -- A 46-year-old man who mowed down and killed a Toronto police officer with a stolen snow plow may have been mentally ill, but he was still capable of knowing what he did was wrong, a jury was told Friday.

Richard Kachkar meant to kill Sgt. Ryan Russell, 35, when he drove the plow straight at him, or at the very least, in trying to evade police he drove dangerously at Russell and knew that would likely cause his death, the Crown said in its closing submissions.

Crown Attorney Christine McGoey urged the jury to find Kachkar guilty of first-degree murder. The defence has urged the jury to find Kachkar not criminally responsible by reason of mental disorder.

There's no dispute that Kachkar stole a snow plow on Jan. 12, 2011, drove it around Toronto for two hours in the early morning, hitting cars, running red lights and driving into oncoming traffic, and at about the halfway point the plow struck Russell, fracturing his skull.

What the jury must decide, as the nearly two-month trial draws to a close, is Kachkar's mental state at the time.

Kachkar, who court has heard yelled about the Taliban, Chinese technology and that "it's all a Russian video game" on his rampage with the stolen plow, did exhibit some psychotic symptoms, McGoey said.

"There was a mental disorder of some kind," she told the jury. "It's our position that it's a matter of degree. He was sad. He was lonely. Things weren't good in his life."

Kachkar had plenty of time to avoid hitting Russell, but he didn't, McGoey said. Kachkar wanted to commit suicide but didn't want to actually do it himself, so he may have tried to force that on Russell in a "kill or be killed" situation, she suggested.

Just because someone has a mental disorder, doesn't mean that is the only thing operating in their mind, McGoey told the jury.

"The question for you to decide is to what degree did his mental illness impact on his capacity to appreciate the nature and quality of his acts or his capacity to know the acts were wrong?" she said.

Russell had been trying to stop Kachkar around 6 a.m. that day. The dashboard camera from Russell's cruiser shows the plow doing a U-turn and then driving toward the police vehicle. Russell reverses as the plow comes toward the cruiser. The plow is briefly off camera and witnesses testified that in that moment Kachkar slowed the plow and opened the door as if to get out.

Russell then got out of his cruiser and Kachkar accelerated at him, witnesses testified. The plow clipped the driver's side front corner of the cruiser and Russell fired three shots toward the plow as it continued at him, but he was struck, witnesses said.

Ontario Superior Court Judge Ian MacDonnell told the jury as he began his final instructions to them that they can find Kachkar not criminally responsible only when they are satisfied that his mental disorder rendered him incapable of knowing his actions were wrong.

The jury's first task, MacDonnell told them, is to consider a not criminally responsible verdict. If they believe Kachkar couldn't appreciate what he was doing, their deliberations end there.

If they don't believe that, the jury must go on to consider murder or manslaughter, MacDonnell said. If they believe Kachkar meant to kill Russell, meant to cause him bodily harm likely to kill him or was committing a dangerous act that he knew could likely kill Russell, the jury must find Kachkar guilty of murder, MacDonnell said.

Kachkar would be guilty of first-degree murder if the jury believes he knew Russell was an on-duty police officer.

If the jury finds Kachkar is criminally responsible, he is at the very least guilty of manslaughter, MacDonnell said.

The judge is expected to finish his jury charge Monday, at which time deliberations can begin.