Bringing Gannon home is THE #1 most important thing. I agree with
@MassGuy that they know where to look for him, but need the snow and ice to melt before they can access the area. Knowing that there wasn't a lot of snow the day he disappeared, and that there's been a lot of snow since then, this makes sense.
I'm not sure LS is up to going through a trial where all of her lies are exposed. The thought of being humiliated in that way may just be enough to get her to plead guilty. Of course the public will still find out all/most of the details, but she wouldn't have to face it in a courtroom. She does not like to face anything head on, as we well know by her first interview and her hiding from the camera yesterday.
Those of us raised by someone with a significant personality disorder tend to become very empathetic people. It stems from having to anticipate the parent's moods, reactions, needs, wants, etc. I'll even say I have found that I have to guard against some of the same behaviors taking root in myself, which with therapy and healing I've been able to do. (Thankfully! I can't imagine doing the things to my children that were done to me!) Speaking for myself here, this tendency towards being "trained" to feel the feelings of others, and how much LS reminds me of my own mother, I'm betting she'll plead guilty as a way of not having to face her true self laid out in all its ugliness.
The only thing that gives me pause is her hatred of Landen. She knows she has won in this "hurting contest" (which Landen wasn't even participating in). She may suffer through the humiliation of a trial just because in her mind she's victorious in taking Gannon away and knows Landen will always suffer the most. And that was the goal.