Did the family do it?
I've thought about it a lot since I saw the movie back in March. You get this call saying that the little boy you KNOW is dead is actually alive, and what do you say? If you in fact did kill him-- You can't tell them you know for sure the boy is dead because to the world he is still missing. But why couldn't they have simply questioned that the boy was who he said he was? He clearly looked and sounded different so everyone would've understood their doubts, and obviously if they asked for a DNA test (or I kept thinking--dental records?) they could get one and prove it wasn't him. I don't think that would've made anyone question the family or suddenly suspect a homicide.
Have there been any other cases like this? I feel like 99% of people would say if only a couple of years have passed, they would know if they are looking into the eyes of their own child. I suppose there could be some level of denial, but it's just so hard to believe.
And remember what Frederic said Jason (the brother)'s reaction was to him? It was really really suspicious. Based on that account, Jason seemed to be the only one who couldn't keep up the "charade"