I think things may not be simple.
Where did the alleged incidents occur (eg UK, NY?)? What was the law in that jurisdiction? Did Andrew have diplomatic status? Is he willing to talk to the FBI? Is he willing to go to the US? Is the existing evidence sufficient to merit an interview?
Also, is the harm worth the prize?
From a UK perspective, I think Andrew has been on a last warning for some time, as he has a bad habit of cocking things up. By all accounts, he also seems to be a little bit arrogant.
On the other hand, he's a veteran who saw active service, during which he was put in harm's way. So he's going to have support for that reason, if no other.
Obviously, the teenagers want justice to be done, at least as far as it is possible, and some/all of them seem to be genuine victims. So that also is important.