The one thing that makes me think he might be the one is, he (allegedly) wrote details in his letter to the Ramseys, that no one other than the PD and DA were privy to.
However, his story is getting weirder and sicker by the minute...
If he was living 1/2 way across a continent, when she was murdered, how did he get into the house, into a room only the family and a couple of workmen even knew existed?
He says that he drugged her and gave her alcohol, but neither of these things were found in her body.
He says that he killed her by acciden t. How is bashing in her head, choking her, and then garroting her an "accident"?