Shoot this guy in the face broken

[ScubaSam01]

Alright so..... I went to complete this easy mission. I shoot him in the face, he dies, and the quest doesn't complete. Face McShooty is dead on the ground, yelling at me to shoot him. I can't talk to him or anything. If I try to re-enter the area, he is already dead, still yelling. I've tried restarting the game, and the console. Not sure what else to do, except for maybe completing the quest on someone else's game? 

 

This is also my last quest for Did it All, so it'd be pretty cool if I didn't have to do all of that again....... Anyone have any ideas? I can't seem to find anything online about this glitch.