Ontario's police watchdog says it has re-opened its investigation into how a protester was injured at last year's G20 Summit after seeing new video evidence.

Canute Fernandes, 42, was on Queen Street West just east of Peter Street on June 26, 2010.

Police arrested him after he was knocked to the ground. He sustained a broken arm and shoulder.

The province's Special Investigations Unit probed the incident, interviewing eight police officers and three civilian witnesses.

In a press release, the SIU said its original ruling was inconclusive because it could not determin whether Fernandes was injured by police or fell while fleeing protestors.

Also, the SIU ruled it could not identify officers who made the arrest.

However on Monday SIU learned of additional video of the incident from Reuters, prompting it to re-open the investigation. SIU wants to interview two men who were nearby when Fernandes was arrested.

A section of the Reuters video shows Fernandes on the ground being arrested by police, but does not show what caused him to fall. Two men are seen standing to his right. It's those men the SIU wants to interview.

"[The video] shows Mr. Fernandes landing on the ground and a number of police officers taking him into custody," SIU spokesperson Frank Phillips told CBC News. "To the right of where Mr. Fernandes landed … you can see two civilians there and one of them appears to have perhaps a camera."

The SIU asks anyone who can identify either man in the video to contact them.

"We're thinking that perhaps they may be able to shed some light onto exactly what happened here," said Phillips. "We're trying to determine exactly how it is that Mr. Fernandes became injured."

Anyone with information, is asked to call SIU at 416-622-2342 or 1-800-787-8529.