Here's what I think may have happened (and I think it, because having spent a part of my life as a teacher, I have seen this sort of thing play out a lot)
1. Something happened and the girl's dreads got cut off, maybe by a "friend" or some other person. Maybe it was as a result if a bet or a dare. Anyway, the how and why of it doesn't matter.
2. She didn't want to get the real culprit in trouble so she lied to her parents and blamed the two boys.
3. The parents made a WAAAAY bigger deal out of it that she expected, so she was really forced to either go along with it, or to admit the lie. She tried to ride it out.
4. In the end, things got way more serious, the press the publicity, and she was really forced to own up.
As for the media, what possible reason could they have to disbelieve her. If she seemed credible and her parents supported her story, there was no reason to question it.
IMO, this whole thing is a just a big, fat nothingburger - a pre-teen lied and things got out of hand. Nothing to see here folks, everyone go home.