I think people are forgetting one important fact.
According to what I heard on FoxNews last night, the local authorities had told Patsy before she died in June that they were planning on arresting this guy. To me this means that they have strong evidence linking him to the crime. He may just be confessing to get sent back to the US instead of dying in the Thia jail.
Karr was never IN a Thai jail. He was picked up in his apartment at the request of US authorities.