The teacher has failed both children.
If she had read him the riot act and marched him to the Principal's office and he had taken appropriate serious action for this, then indeed the police may have been avoided.
But the teacher wasn't interested and now there will be consequences.
That boy was an absolute pup of the highest order to touch the OP's daughter.
The school are a disgrace that it's teachers don't know the very basics about how to react to such a serious incident.
In my boys school that they attended, recently a 13 year old was send home for a WEEK for taking the phone of another boy and sending his mother a vulgar message.
His parents were called and he was frog marched out of the school.
Possibly an over reaction but it sent a clear message to new entrants to the school they have a low tolerance for poor behaviour.
Any decent school would expel a child for this and they would be correct IMO.
All children have abasic right to not have a hand laid on them in school.