LE don't feel that any of the family did it, and they surely have more to go on than we do.
My gut feeling is the child was being abused by some fairly regular visitor, but the fam don't know exactly which one. There was some DNA, male, maybe "planted", which I really don't think the family are criminal enough to do. Their choice of friends is just awfully questionable.
(One example, S. Stine, allegedly impersonating an LE person, and not letting police in who were responding on the 23rd to an interrupted 911 call. They didn't have a warrant, so they couldn't insist on entering?)
Another thing, ST's book says there had been a kitchen remodelling just before Thanksgiving which the family didn't mention to police. Thanksgiving is only a month before Christmas.
But I really think it was someone at the party on the 23rd, who maybe overheard the Whites inviting the R's to their house for Christmas Day.
Re The Unfamiliar Blue (?) Van parked across the street that morning, which JR noticed but did not really report to LE....Sorry, I don't remember which book, maybe DOI.
Was any neighbor on vacation, so that their driveway may have been used by someone else? The Barnhills' boarder, GM, crashed the party on the 23rd, saying the dogs were barking and he got nervous across the street by himself. Was someone from that van sneaking around? I'll bet some neighbors were away for the holidays. Also, hadn't a couple of unfamiliar vehicles been seen, and does anyone remember which day?