I haven't been following this case as closely as some of you -- is there any chance that he and Sarah were involved? It's been stated that he was looking for a girlfriend after his last relationship ended, and young girls can be very impressionable. To have an older guy give you attention can be pretty heady. I just wonder if she had no idea what she was getting into (being young), and he was mentally unstable, and this turned into some type of obsessive thing. Maybe her mom found out about them, decided to put a stop to it, enlisted the help of her friend, etc., and he wasn't going to let anyone come between them. (JMO) I hope I'm wrong, but why spare her, and kill the others?