There is VERY little information here to go on, Matou. We don't know what happened other than what her mother says, who wasn't there and didn't learn about what happened until several days later when it was too late to do forensic evidence.
What we do know is there was a photo of some sex act that LE declined to press charges about, all the participants were minors.
We also know that after her family moved her to a new school to give her a fresh start she was STILL receiving messages - often from strangers - asking for sex.
How did THAT happen is what I'd like to know. How was she made to keep the same phone number, the same internet/social media ID, where there is no where on the globe she could go and not keep accessing this abuse?
That harrassment, in my opinion, is black and white.
The sexual behavior - I don't know.