I'm going to say this now, before we get started. You won't like it, but trust me, I've done this more times than I care to punish myself remembering. In a case like this - a kid - nine times out of ten it's someone close to home. Family, friend, neighbour, someone in the community. Don't forget that. However distraught they look, however unlikely it seems, they know who did it. Perhaps not consciously, and perhaps not yet. But they know.
They know.