The very first thing he did when he took the stand on cross from the DA was to admit that he had lied about a material fact of the case, allowing the jury to be instructed that the rest of his testimony was untrustworthy. He did a pretty spectacularly bad job on the stand.
I'm surprised he went down for murder 1, but there was a pretty damning array of things lined up against him. Aspergers or not, he admittedly ripped up and flooded his car while trying to actively hide it from the police in a storage locker; he claimed a 6-inch(!)-wide blood stain on a bag (not a sleeping bag, but its pouch) in that car was from having sex; and finally, he built his case not on the premise that he didn't kill Nina, but that she was still alive --- a very simple assertion for the DA to knock down.
I'm surprised he went down for murder 1, but there was a pretty damning array of things lined up against him. Aspergers or not, he admittedly ripped up and flooded his car while trying to actively hide it from the police in a storage locker; he claimed a 6-inch(!)-wide blood stain on a bag (not a sleeping bag, but its pouch) in that car was from having sex; and finally, he built his case not on the premise that he didn't kill Nina, but that she was still alive --- a very simple assertion for the DA to knock down.