Isolate the kids: Ask them about the “camping trip” and if Daddy stopped at the dump to drop off some bags of “garbage” on the way.
I subscribe to the theory that in every liar’s story there are bits of the truth.
i.e. He definitely left the home at midnight with the kids.
He did go into the woods near a public camp site.
He says his wife is “out there somewhere”.
Everything else is *filler*.
Police have interviewed in the older boy, who I’ve read is nearly 5. Needless to say, they’re not going to be disclosing the results of the interview for a while.