The Independent Office for Police Conduct (IOPC) has confirmed the officer captured on video appearing to punch a suspect several times is under criminal investigation.
The video gained significant attention on social media when it emerged last month.
The IOPC said it had “notified a police constable that they are under criminal investigation and have served them a gross misconduct notice”.
They said the development did “not necessarily mean that criminal or disciplinary proceedings will follow”.
North Wales Police have suspended the officer, the IOPC understands.