This is how Charlie’s assassination went down.
There were two hits (This explains the signals from the security guys to do both simultaneously) the "Mic Bomb" detonated by Brian Harpole and the pistol-camera fired by Rick Cutler—who was positioned above and behind Charlie.
This would explain the holes in his neck and shirt caused by the bullet's trajectory.
A level of sophistication that confirms Mossad and CIA involvement.