Another cell phone video has emerged showing a BART police officer striking Oscar Grant in the face, knocking his head backward and staggering the 22-year-old man who was eventually killed by another BART officer.

The officer who punched Grant in the video is the same officer whose knee was on Grant’s head when Johannes Mehserle shot him in the back.

The new video aired Friday night on KTVU-TV in San Francisco.

According to the San Francisco Chronicle, the officer’s name is Tony Pirone. He is now under departmental investigation.

He and the other officers present at the time of Grant’s shooting all remain on paid administrative leave while the investigation continues, but until Saturday BART was not investigating the conduct of anyone besides Johannes Mehserle, 27, who shot Grant.

After he was punched, Grant can be seen sliding down to a sitting position and raising his hands in compliance.