Sue the school. Then you will see how fast the school will move to find the culprit. Sue the boy and his parents. Have a lawyer and investigator look into the boy and his family. Any problems found can be brought to the authorities. Police sometimes don't do anything but I can guarantee that child protective services will make sure that the bully is placed in foster care far away from you. Oh, and get the local and national news involved. Schools are very scared of the news.