Washington  - The Chinese immigrant who brutally stabbed, beheaded and then ate the flesh of his seatmate on a Greyhound Canada bus last July, on Tuesday pleaded not guilty to a charge of second- degree murder.

A statement of events on the bus that night was read out in a court in Winnipeg, Canada, as the trial of Vincent Li, 40, started Tuesday. It said Li apologized to police when he was arrested for the gruesome killing of carnival worker Tim McLean, 22, and pleaded with officers to kill him.

The court heard that the unprovoked attack was so violent that many parts of the victim's body could not be found, the Canadian Broadcasting Corporation reported.

The attack took place on a Greyhound bus traveling along the Trans-Canada highway from Edmonton to Winnipeg. Li stabbed McLean with a large hunting knife as 36 passengers watched. The driver pulled over to allow the others to disembark, and they stood on the highway watching the grisly murder unfold as they waited for police to arrive.

According to witnesses, Li beheaded McLean and walked to the front of the bus holding the head. Police had by then surrounded the bus, but chose not to storm it. They waited until Li shattered a window, threw out a knife and scissors and then jumped out.

As police and passengers watched, Li proceeded to cut off parts of the body and even eat some. When they finally apprehended him, he carried a severed ear and nose inside a plastic bag in his pocket.

The court was told Tuesday that Li had no criminal record and came to Canada from China in 2001. He worked as a supervisor at McDonald's, a church caretaker and a newspaper carrier.

Defence lawyers have argued that Li is mentally ill and cannot be held criminally responsible for his actions.

McLean's family has been lobbying for a change in legislation, which would prevent a person found not criminally responsible for a crime from being released into the community - meaning that such a person would face life imprisonment.

Mclean's mother told CBC she never wanted to see Li released from custody. (dpa)