Pretty obvious who the main POI is since they aren't releasing exactly what brought the charges forth in his arrest. It's not separate from her death. IMO.
From the presser, they pretty much have it solved, it's just how and gathering the evidence to secure and present for probable cause. I'm betting they found her body by way of his cell phone. He place her body there on his way back home to San Angelo. Did he set up the "dinner date" and the place to meet via the internet pretending to be someone else.? The meeting place was the lot where her car was found, imo....and him showing up must have been a rude awaking to her.
It's scary enough to meet someone thru friends, work or family...because they really don't know all there is to know about someone; but it's like going out with an alien from someone you meet on the net. Can not for the life of me understand why or how anyone could feel secure in doing it. IMO
ETA: Link for presser. Hope this works!!
http://www.youtube.com/watch?feature=player_embedded&v=Aik5Ar3Nzzg