I wish the video was better. You can clearly see an "object" bounce on the ground long after he was shot and the police were standing around him. I cannot tell where the object comes from. It could have been tossed away from the man on the ground to keep it out of his reach after he was shot. It could also have come from a cop who carries an extra gun to drop in case of a need to cover his/her butt.  Fingerprints should be on it from the dead man if it was his gun. Unfortunately, cops investigate cops.
99% are probably good cops but I've seen first hand where they also have a code of silence for covering the bad ones.