From another thread regarding sexual assault in school:

Former building administrator (now district) from a whole different state. Not sure if this will help.

Get a restraining order. In my state our suspensions can only last until the end of the school year (unless it involved a gun) then we have to bring the student back at the beginning of a new academic term. We have to.

Legal advice won't like this but the law protects everyone's right to an education, including students who assault or harm others. Even if their presence infringes on their victim attending school.

We recommend to parents that they get a restraining order. Our state restraining orders can exclude school, so we have a copy of what the order looks like and we show parents that exact box we need the judge to check to ensure school is included.

This will be an uphill battle since you didn't file a police report.