TORONTO -- Ontario's police watchdog says there are no grounds to charge two Toronto police officers whose use of force during an arrest this spring left a man with bruises and a concussion.

The Special Investigations Unit says the officers had the lawful authority to use force in arresting James Ross Kennedy on March 24 because he became aggressive "for no apparently legitimate reason."

The SIU says the confrontation stemmed from Kennedy's mistaken belief that the plainclothes officers at his door "were either members of the Jehovah's witnesses or drug dealers."

The agency says a statement from one of the officers maintains the pair identified themselves as police and one of them showed his badge.

The SIU says the officers moved to arrest Kennedy after he grabbed one of their sweatshirts. But the 26-year-old resisted and all three fell to the ground.

The officers had knocked on Kennedy's door while looking for a potential witness to a homicide, but the person they sought didn't live there.

The SIU is an arm's-length agency called in to investigate whenever someone is killed or seriously hurt while interacting with police.

It also probes allegations of sexual assault involving officers.