It is a well known trick in the US to put a knife in the victim's hands after you shoot someone. That way you can claim self-defence.
This Rambo here is a professional. After he shot the two guys, he calmly went over there, took out the guy's gun and put it in his hands to make it seem as if he had drawn it, and then photographed it as evidence.
I suspect he is too smart to leave his prints on the victim's gun, but it would be worth checking anyway.
nice views man, makes some good sense