So very sad...
Please take it to the authorities, even if nothing is done you will be able to feel better knowing that you at least tried.
I for one will always error on the side of support of a victim, if I'm wrong. Shame on them. If I'm right, I was one less person to harm the victim for speaking up.
I have been on the other side when my daughter accused a fellow JW of molesting her. Many believed the molester over her which tore at our heart..."how can they doubt someone brave enough to speak up?" Well in time the creep admitted to being a child molester and those people who believed him were left feeling quite foolish for taking a stand on his side.
My opinion...Offer a kind word and sit back and wait for it to be proven or not. Don't add salt to an open wound by calling someone a liar before you know for sure.