I think we just have to be open to all possibilities here.
There is just too much here that makes me think that a prior poster's interpretation may be correct - that her statement of "call the police if I'm not home by 6" was possibly something TC told her to say, as a way to hopefully buy them until 6PM. If she's telling friends she can't make plans after Monday because she might not be allowed, it may just be that she couldn't say to them "because I'll be gone" without giving the whole thing away. If she truly had no intention of leaving with TC then the whole 'can't make plans after Monday' thing makes no sense. If he's researching teen marriage and she's posting WIFE on her profile not long after, that says something to me. None of that makes her any less of a victim. He's just apparently a pretty skilled manipulator who can fool even pretty educated people, so why would a young girl be any more immune?
Can someone clarify: Did the phones ping at 3 or were they found at 3? It should not have taken until 3 for them to drive to Decatur, so one has to wonder if they pinged at 3 why they weren't further away by then. If they were found at 3, then who knows how far they could have gotten by then?