Bass, 42, was surprised by Barnes, who had broken into her home while at work, then robbed, beaten, stabbed, and killed by a headshot.
Barnes's conviction was based on forensic evidence and witness testimony placing him at the crime scene.
His fingerprints were on a bedside lamp that was used to bludgeon Bass, traces of his semen were present at the scene, and two patches of blood on his clothing were confirmed by DNA analysis to have been hers.
He had been unable to afford his lawyers, and the Wichita County Public Defender's office was not equipped to handle his case, so two local attorneys were appointed for him.
European anti-death penalty activists contributed some $16,000 to his defense fund, and the new lawyers paid for forensic tests out of their pocket.