My 14 year old autistic brother

Hi! I’m just reaching out to see if anyone with an autistic teenager could give me some advice. My younger brother was diagnosed with autism when he was pretty young. He has always been a sweet boy, but over the past year his behaviors have gotten more violent and sexually deviant. Not only did we find camera footage of him hitting my dog and holding her down, we also found footage of him messing with her private parts and coaxing her to lick his penis. He was also suspended from school for taking a younger girl behind a shed at recess where he told her to “get on her knees and close her eyes for a big surprise”. We later found out that he stole a computer from school and hid it in his room, where he was watching porn about girls peeing. In the past year he has grown angrier, even hitting and choking out our 12 year old brother. I have no idea what todo and neither does our single dad. Let me know what your thoughts and experiences are! Thank you!