if you're worried about the computer that he was using, just take out the hard drive and use a sledge hammer on it. Make you break the cylinders up pretty good, then toss it in a garbage can behind a grocery store or something. Go out and buy a new hd, they're super cheap anyways. If you try to use software to hide your tracks, the feds can obtain the info off your drive espec. if you don't know what you're doing..the easy way is the sledgehammer.