This kid keeps touching himself

I 15 (f) have been going to this new school and I really hate it. I am in 10th grade and this new kid showed up to school 3 weeks in bc he got kicked out of his other school. He showed up and the 2nd day he was here he was seen touching himself in class and has gone to the bathroom and come back with “stuff” on his shirt. He’s come back saying he was touching himself and the teachers hear this and do nothing. He makes all of the kids here uncomfortable he has stared at mine and my friend’s legs. It’s uniformed and I was wearing a skirt to school he bent under the desk while he was sitting in front of me and was staring at my legs and crotch. He grabbed my ass in the lunch line like after grinding up on me. He also tried to touch my guy friend’s privates. I have told teachers and they say they’ll talk to him nothing has happened with him. I’m scared to go to school bc I’m scared he’s going to touch me and I already have trauma from when I was younger. What should I do??

Update: I told the dean of students and so did my parents and all of my friend’s parents. He got 1 day of iss and is back tomorrow