I don’t know anything about how to handle this situation, but don’t let it go.
I would talk to the principle and find out why your daughter was questioned with you present especially since if the principle had done his/her job, it would have been clear that your daughter could not have been involved.
I would also follow up with the police and file a complaint that your daughter was questioned without your consent or knowledge.
And I would contact a lawyer, and make sure that the school district know you have contacted a lawyer. They appear to have really screwed up in this case.