What's troubling about the case is that the boys had two weeks on their own to get their act together.
It's clear that this crime is dependent on finding a body. That's why someone had to get rid of it so that it would NEVER be found. It's so elementary :) No confession is likely to be forthcoming...
So now what??
Just like they do in the movies, tell each one of them that the other is talking and it would go easier on him if he confessed. I can't believe one of them hasn't cracked yet. I thought they were talking when the local cops started questioning others and arrested Croes.
Although it's very possible since Daddy dearest is a judge in training, he told them the possibility of no conviction if the body isn't found. If they know she won't be found then they have no reason to talk/confess. This could have all been cooked up when they were set free in the beginning of the investigation. Big mistake IMO.