One detail about the Ramsey’s behavior: does it prove anything?

Ok follow me down this road for a second.

Was it ever officially confirmed that she had been previously SA’d?

If yes, did the Ramseys ever comment on this or try to figure out what the fuck happened? Wouldn’t following that clue lead to a potential killer and at the very least catch an evil pedophile?

If no, doesn’t the lack of interest right there alone prove they’re guilty of something? If this was my kid I would go on a crusade to figure out who had been abusing her. So based on this behavior, it seems plausible if not certain they had something to do with either the SA, murder, or more likely both.

Right?