As I've said before, I'd say they're watching the person who's involved and waiting for them to screw up big time! There's too many obvious oddities from day one in this case. But, the fact remains and there's no escaping this, one day when they're number is called, they're going to answer to the man above for this.
I agree and have from day 1. LE is hoping either the alleged kidnapper or the person who helped her run away will tip his hand.
I still go back to an early plea by Lois Smart (paraphrasing), telling the person involved that it wouldn't work out for him to have her for himself -- words to that effect. That's not something one would say to a suspected bonifide kidnapper. Those were words that sounded like the mother suspects someone either took her or cajoled her into leaving so he could have constant access to the girl.