Looks like he was shot above the left eye. That probably killed him instantly, so that's why he fell to the ground and his eyes are still open. Then then they pumped two more bullets into his dead body in the upper back just for good measure.
I like how the one examiner has his hand between the guys legs -- feeling for a bulge perhaps? And kudos to the killers for insisting the guy take off his shirt before they shot him.
He was half naked to begin with -- no shirt, and no shoes. If you are going to point a gun at his face, you can easily pull his pants down. They are certainly loose enough, and he won't argue about it. In fact, he's probably hoping you'll suck his dick or even fuck his ass instead of shooting him.