Don Brasco was a FBI agent doing undercover work. One night Don and his accomplices drive up to a shack. The others get out of the car and instruct Don to stay in the car. Don does not know why they are there.
After the others go inside the shack they get in an argument with a rival gang, and Don’s accomplices murder all the other gang members. They had brought their guns with them, and were planning to murder the rival gang members all along.
One of the accomplices walks back to the car, pulls a gun at Don, and instructs him to enter the shack. Within the shack the others instruct Don, at gunpoint, to help them saw the rival gang members in to pieces so they can be carried back in the Cadillac. Don, fearing for his life, proceeds to butcher the dead rival gang members in to pieces.
Is Don guilty of mayhem? What are his defenses?