I live in Cook county of Illinois. You have to be very careful on how you would react to such a situation. If you actually did grab his arm and try to drive away dragging him, you would likely be held responsible for his medical bills and you would find yourself in serious legal trouble. In the eyes of Cook (a.k.a."Crook") county, this poor soul was not necessarily trying to harm you, he was JUST trying to get money to support himself. If he is simply trying to steal from you, you should call 911 and wait for the police to arrive.