If you don,t catch him with the co, have the police trespass him from your property. All this does is give him a formal warning from the police that if he is proven to be on your property again, he can be arrested. I would then set up an infared trail cam over one of your traps. I know this can be pricey, but worth it because he'll get a stiff penalty, plus you'll still have a nice trail cam!