A criminal investigation has been launched into the police officer filmed kicking and stamping on a man at Manchester Airport.
The police watchdog, the Independent Office for Police Conduct (IOPC), said it was investigating the officer caught on camera earlier this week.
A decision will then be made on whether to refer the matter to the Crown Prosecution Service and whether the officer involved should face disciplinary proceedings.
A Greater Manchester Police (GMP) officer was suspended on Thursday after the footage was shared widely on social media.
It showed an officer kicking and stamping on the head of a man who was lying face down on the floor, with a woman kneeling beside him.
The officer was later filmed pepper-spraying another man before wrestling him to the ground.
Police said three of their officers had been assaulted in the incident, including a female constable who suffered a broken nose, and four men were arrested.
The video sparked two nights of protests outside Rochdale Police Station and Manchester city centre.
MPs call for calm
Andy Burnham, mayor of Greater Manchester, previously urged people to remain calm in their response to the footage.
The mayor told the BBC that the full footage of the incident showed a “fast-moving and complicated” situation that was not “clear cut”.
He added: “There are issues for both sides, but that said, it is right the officer has been suspended.”
Paul Waugh, the Labour MP for Rochdale, said while there was “clearly deep concern”, he warned against the issue being hijacked by extremists.
He pointed out that the family of the man who was kicked have also appealed for calm following the protests that saw demonstrators blocking tram lines and roads in Manchester, adding that “they have no political agenda”.
Former Rochdale MP George Galloway said he knew the family who were involved well, and planned to visit their home on Friday afternoon.
Supporting calls for protests to remain peaceful, he said: “We don’t want anything distracting from where the focus should now be, on the investigation and getting it speedily and properly completed.”