Are you a teacher or an administrator? As a teacher, I definitely get the same thing. I usually tell them that my glasses give me perfect 20/20 vision.
It’s been my experience that, generally, when I send a kid that swears up and down that they haven’t done anything wrong to the office, once said kid is being grilled by the principal with mom or dad in tow, most kids cave and admit to their wrongdoings. It’s even more effective if the entire group is called in, one by one. They nearly always give enough detailed information that matches what the others say that a competent administrator can arrive at the truth. NOTE: I said COMPETENT.
Seems to me, she will now be labeled as an even bigger outcast not only by the kids bullying her, but also teachers and admin. She will be known as “The girl who was hauled off in cuffs”. This will only exacerbate the problem. Parents of other children in the school will probably caution their kids not to associate with her, compounding her loneliness and despair.