sorry but I'm afraid you're information is off. The original poster had good information. Zack was involved in an accident sort of. He was in the process of setting off an explosion in one of the labs when hodges walked in. He kept his finger on the trigger too long and the bomb went off resulting in his being badly burned and it led to his getting accused of being a serial killer. he's currently being held as mentally incompetant to stand trial. Dr Sweets was the only one that knew he wasn't insane. Because of the way his mind works people just think he's insane.