Ontario's police watchdog says there are no grounds to charge two Halton regional police officers in the fatal shooting of a man in Oakville.

The Special Investigations Unit's director Ian Scott says the officers were "justified in the use of lethal force" against 43-year-old Kyle Newman on Jan. 12.

The SIU says an officer was leaving the police division parking lot in Oakville that day when his cruiser was intentionally struck from behind by Newman, in a silver Nissan.

The agency says the officer drove away but was pursued by Newman and rammed again, so the officer called for backup and returned to the parking lot.

Newman again rammed the officer's vehicle and another vehicle before getting out of his car and walking toward officers with a large knife in his hand.

The SIU says officers shouted at Newman to drop the knife, drew their handguns and pointed them at him, but he did not comply and two officers fired their guns when he charged toward them.

Eleven bullets were fired at Newman, including the fatal shot that struck him in the head, according to the SIU probe.

Police have confirmed that Newman was the estranged husband of Katherine Newman, who was found dead in her Oakville townhouse the same day.

"While there is a tragic lead-up to this incident, for the purposes of my analysis, it is not directly relevant to the SIU's investigation," Scott said.

"What is material are the circumstances immediately before the shooting."

"In my view, both subject officers were justified in the use of lethal force leading to Mr. Newman's death in these circumstances," Scott concluded, referring to Newman's "apparently purposeful approach" toward them while brandishing a knife and his failure to comply with police demands.

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.