I've been following along, and honestly, can't believe that it's been this long without Sky being found. However, I think that they haven't charged Julia with any related to Sky because in the long run, it limits their legal options. If they charge her for neglect for leaving little man in the car, it's the same as saying they believe she left him in the car. Then, in the future, when/if evidence comes to light that he wasn't in the car, their credibility for all future charges is shot. If they charge her with neglect and it comes to light later that he died of direct abuse, their options are limited. If they charge her with obstruction of justice, they have to be able to pinpoint exactly which parts of the story she's lying about, and if they are wrong, when they do find him, or God forbid, his body, they have to stand by the statements they made when they charged her for obstruction, some of which might actually bite them in the rear and make it nearly impossible to charge her for what really happened.
The worst thing to have in any criminal case is an unflappable suspect. No matter how unikely a story, if the suspect sticks to it and there is no direct hard evidence that proves them to be lying, then it's actually incredibly hard to bring charges. Especially when there are so many unknowns.
This is all MOO. I'm not a professional, but I almost have a bachelor's degree in Criminal Justice Admin. (3 more weeks, go me.) We've kicked this around in class a lot...what happens when the suspect insists that the highly unlikely story is the truth and is basically unflappable? It would be so nice if she would just break down and tell the truth, whatever that might be.