I don't know. I keep reading this (here), but it doesn't strike me as all that convincing. This is not the Anthony case. Here, the father was nearly 1,000 miles away at the time she disappeared...which in this case, is much more definite. I think if they get enough to charge JP, and his defense tries to suggest SP was involved...they will have a serious uphill battle. And unless there is actual, verifiable, credible evidence placing him closer to the SLC area, they will be laughed out of court.
And I don't think JP will get off by arguing that his daddy was a bad influence on him. I think most juries would listen to that and dislike him even more. He is just not appealing on any level, and that will help sink him.