NORRISTOWN, Pa. - Norristown police are investigating an altercation between an officer and a suspect they say happened on Friday.Video of the encounter, which occurred on the 200 block of Franklin Street, has been shared on social media.That video shows the officer, identified by the department as Sean Gallagher, punching the suspect twice in the head.The suspect has been identified as Malcolm Coleman, who police say was wanted for a probation violation and aggravated assault with a firearm.Norristown police say prior to the moment when the punches were thrown, Coleman reached for his waistband and told officers he was "not going back to jail."Officers deployed a taser, but say Coleman continued to resist arrest.