If this guy is involved in karting, why can't the karting community take care of him? Surely he shows up at a race track sooner or later. Take care of your business, then call the authorities to pick up what's left of his after his lesson. If he's been reported before, evidently the normal channels haven't gotten through to him. I'm not kicking his victims, but if he burned me, I would do everything in my power to make sure he didn't want to do it again, whether through the authorities or my means. Getting on here and crying about it accomplishes little, only to be able to compare horror stories. Get together and make something happen.