A Toronto police officer is facing a criminal charge for an alleged June 26 attack on a G20 Summit demonstrator named Adam Nobody, Ontario's Special Investigations Unit said Tuesday.

In a news release, the arm's-length agency noted it first ruled that while Nobody appeared to be roughed up, it was impossible to identify the perpetrator.

YouTube video had been shot of that incident, in which Nobody is seen being swarmed and at least one officer can be seen making a punching motion. Nobody had to be treated for a fracture below his right eye.

Toronto Police Chief Bill Blair asserted in a Nov. 29 interview that the video had been significantly tampered with.

"He said that the police were arresting a violent armed offender and that a segment depicting the use of a weapon had been removed from the tape," the SIU said.

John Bridge, who shot the video, said there was a gap because he turned his camera off for a few seconds, then turned it back on when he saw Nobody being arrested.

He supplied the SIU with his original video, which was of higher quality than the YouTube version.

Blair issued a statement on Dec. 3 that said he had no evidence of any attempt to mislead with the original video -- and no evidence Nobody was armed.

On Dec. 9, the SIU received new video from the Toronto Star. A member of the public also provided a third video, and the Toronto Police Service gave the SIU a list of 15 officers who may have been in the area where Nobody was taken down.

The SIU designated 12 of the 15 officers as witnesses and three as subject officers, meaning they were under investigation.

"The twelve officers who were interviewed were shown the Bridge video of the incident and stills taken from other videos," police said.

"None of the twelve witness officers who were said to be in the vicinity of and/or involved in the arrest of Mr. Nobody were able to positively identify themselves as being depicted in the videos, nor could they identify the other involved officers."

The subject officers declined to give statements, which the SIU noted is their right.

Toronto Police Service also gave the SIU the name of another witness officer. He identified one of the subject officers.

Const. Babak Andalib-Goortani has been charged with assault with a weapon. He is scheduled to appear in court on Jan. 24.

Nobody made a second complaint about being taken away and beaten by two plainclothes officers after his initial arrest. The SIU said it has further investigated that allegation and hasn't found enough corroborative evidence to warrant the laying of a charge.

In late November, the SIU also issued its findings on five other cases. It did find that Brendan Latimer, 19, might have been the victim of excessive force.

However, Latimer's eyes were closed when the blows were struck, and so he was in no position to identify his attacker, the SIU said.

In the remaining cases, the SIU said there was no proof the protesters suffered injuries at the hands of police.

The SIU is called in to investigate cases where injury or death occurred as a result of interaction between civilians and police, or where there has been an allegation of criminal assault.

The Toronto Police Service is also reviewing the conduct of its officers. Almost 100 face disciplinary action for not wearing their name tags.

Protesters gathered in Toronto in the days before the two-day summit of leaders from the world's 20 largest economies.

The biggest protest took place on June 26, a Saturday. A small group broke from a peaceful main crowd. Using so-called Black Bloc tactics, they went on a 90-minute vandalism rampage. Business storefronts were shattered and police cruisers burned.

In response, police carried out a widespread crackdown to restore order. The area around Queen's Park was to be a designated protest zone, but the Nobody incident occurred there.

Police arrested more than 1,000 people. About 300 were actually charged with criminal offences, but a large proportion of those have been stayed.

Several other inquiries into policing activities during the G20 remain active.