CHESTER, Pa. - The Chester Police Department says they are investigating a video that surfaced that shows an officer appearing to repeatedly punch a teen during an arrest.Family members identified the teen in the video given to FOX 29 as Bahir Green, 16."My friend came up to me and she was like is this your brother?" says Shaniah Carlton, Green’s sister. "I see him getting punched, punched, punched, and then people started sending more videos to me and I got different angles."Chester police way the arrest happened at 10th and McDowell Streets on Friday morning.Carlton says officers would only tell her that her brother was arrested following a chase and is in custody.