TORONTO - More testimony is being heard from witnesses who saw a snowplow racing through city streets just before it struck and killed a police officer.

Richard Kachkar has pleaded not guilty to first-degree murder and dangerous driving in the death of Sgt. Ryan Russell.

The Crown alleges the 46-year old Kachkar -- who was barefoot and not wearing a jacket -- purposely drove toward Russell's marked cruiser early on Jan 12, 2011.

Ontario Superior Court Justice Ian MacDonnell has said there's no dispute Kachkar was driving the plow, and that it's the suspect's mental state that's the focus of the trial.

During the incident, Kachkar was heard shouting about the Taliban, Chinese technology and a microchip in his body.

He'd rammed several cars with the plow and driven it into a car dealership window before he hit Russell.

The Crown says Kachkar stole the plow at a Tim Hortons when the driver stopped for a coffee break.