A Toronto police officer who was stabbed while trying to arrest a 38-year-old suspect has been cleared in the man's death.

The head of Ontario's Special Investigations Unit says there are no reasonable grounds to charge Const. Jeff Blair in the April fatal shooting of Peter Lumanglas.

The SIU says Blair began pursuing a van after clocking the vehicle travelling at 146 km/h in an 80 km/h zone late on April 15, but ended the chase shortly afterward. 

The officer later saw a man he believed to be the driver walking down a street and after questioning him, arrested him for dangerous driving and failing to stop for police.

The SIU says Blair found a pocket knife and what he believed to be drugs while searching the suspect — later identified as Lumanglas — and informed him he was also under arrest for drug possession.

The agency says Lumanglas lunged forward, grabbed the pocket knife and opened the blade, then stabbed Blair three times before the officer stepped back and drew his gun.

The officer warned the suspect not to move but the man moved toward him with the knife raised above his head, the SIU says. Blair fired three times at the man, who fell and then tried to get up again.

The officer, who was "bleeding profusely" fired twice more, causing Lumanglas to fall back down, the agency said.

Lumanglas died five days later in hospital. Blair survived the knife wounds to his arms and neck.

Ian Scott, director of the Special Investigations Unit, said the officer believed his life was in danger and had the authority to use lethal force.

"He had already been stabbed in the neck area, and Mr. Lumanglas was coming toward him," said Scott, adding the officer had lost a significant amount of blood and could not retreat.

The SIU is an arm's-length agency that investigates reports involving police where there has been death, serious injury or allegations of sexual assault.