I havent read anything about this stuff. So I dont really know anything besides my gut feeling on this one.
My intuition says the dude who confessed is just insane. Depressed, wants to die probably...why not be famous while your at it, say you murdered someone who was all over the news? My vote: hes a poser, he didnt kill her. He wants some fame and an easy ticket to the electric chair. Might as well give him his wish, doesnt look like the real killer is going to be found anyways. But what do i know