Emotionally, I'd say do what the killers want ya to do. Intellectually and to keep yourself out of jail! Yeah seeing if the cops will get involved, might be your first step. However, if that doesn't work! Then it's recon time. Find out if he goes anywhere at night time. Lay in wait for him, and then do the killer thing. Well not actually KILL, but maim and torturing isn'tabove my sense of reasoning in this situation. He doesn't deserve the respect of knowing it's coming. You probably won't get your money back that way, but at least you might can have a good skin sample or even a scalp! LOL Indians had it all figured out. Even the biggest, toughest person in the world, that doesn't see it coming, will fall like a rock.
Either way,good luck.