Life has got to be a living hell for him these days. Hindsight is always 20-20, and if he's like most people, he's probably going back through previous incidents, kicking himself for not picking up on something. I would imagine LE has questioned him at length about noticing something that is missing in the house. I'm guessing they've questioned all the family members at length, and I hope they've been very considerate of their feelings at this point.
From the neighbor's video, it appears she put *something* in the truck, but what? Some have speculated it was a long gun, but I would bet she had the 2X4 in there and didn't want GS to see it - or anyone else in the neighborhood to see it. I hope today is the day they find GS.