A private school in texas is protecting a violent student

I recently left a private school for autistic kids and young adults, but my friend still goes there. It's held in a church and pays rent, so it has a fair amount of money called for the tuition. There is a boy who attends, around 19yo - we'll call him Jim - and he has admitted to having broken a kid's jaw in 2 places in the near past. Lately, he's been making aggressive moves towards my friend (she's 15) and has made several death threats towards another student (who is 12, but is stuck in the mind of an unfortanately annoying 6yo). My friend also feels that Jim is being protected by the head guy for having a rich family and providing money to the school... Also, the head guy (we'll call him Dave) is implementing rules to keep other students from socializing with my friend for reasons that are incredibely strange and implausible (she wasnt anywhere near any incidents that he found her 'at fault' for). He is also talking to her mother and telling her lies about things that my friend 'has done'. He's done the same to me before and my mother, so I belive her. What should we do?