Any child psychologists out there?

Ok, I have worked with kids for 15 years, but something is different about one of my students. He is the biggest challenge I have ever had. His behavior is beyond words. I really want to help this kid but I need to know what is wrong with him first. His mom refuses to get him tested.  He will randomly get up from his chair and go drop kick another child he sees standing up. He has peed in a different teacher's water bottle, not having a clue who owns it. He wrote on the walls with pens. He throws rocks at the heads of complete strangers and other kids.  He tried to drop kick me before. He will throw away other kids stuff like backpacks, shoes or toys. During Xmas we had Xmas lights up around the greenhouse and he decided to take lights off and stomp on them. If he sees a pencil on a desk, he will break it in half. If he sees grapes, he will toss them on the ground and stomp on them. I can go on and on for hours on things he does. He is in first grade and has been expelled from at least three schools. I really want to help him, but I need to know what is wrong in order to come up with a way to help him. His mom is well educated and Dad is out of the picture. Anyone know what is wrong with him and what he needs? Schools don't have the money to hire a teacher's aide, but he he is a danger to my other students.