Another story said he was living in Palm Beach with somebody after his mother died, but he didn’t like it, so asked his friend if he could stay with his family. Most likely he wanted to get back close to the school to do the shooting. He does have a younger biological brother who was adopted into the same family with him.
They’d better locate that brother and keep tabs on him. From what I read BOTH gave the adoptive parents trouble. He’s probably just as nuts, just hasn’t gone off yet.