Personally, I would probably still be giving the parents the benefit of the doubt if it weren't for their behaviour after DeOrr's disappearance... Sometimes searchers don't find kids, sometimes the FBI are wrong, often LE's instincts are wrong, often polygraphs are wrong, often PIs are wrong... It's possible the parents have just been really unlucky and all the experts around them have all come to the same wrong conclusion.
But add in to all that the behaviour of the parents since DeOrr disappeared, and it stretches my good faith too far so I can no longer give them the benefit of the doubt. Their obsession with SM, their refusal to get the word out about their son, the constant collection of donations without a word of where it's going (I'm talking about the online store and gfms, not the fundraising for Klein), the fact that complete strangers organised billboards because the parents never bothered, the constant lies... IMO they have never behaved as if their son is missing and they are searching for him. That's either because he wandered off and got lost and they're such negligent parents that they don't really care and have just moved on with their lives, or it's because they know where he is. JMO.