Tucson police have arrested one of their own for striking a handcuffed suspect while he was on the ground.

Officer William Gallego was arresting a trespassing suspect with other officers late last week when the incident took place.

The suspect had already been handcuffed and was on the ground when Gallego struck him twice in the head with his shin.

The suspect was not injured, but Gallego’s supervisor reviewed body camera footage and started an internal investigation.

Gallego was arrested Saturday and faces one count of aggravated assault. He has been with the force for 16 years.