Byrne killed 25-year-old service station cashier Roberta Johnson with a hammer during a robbery on 14 August 1984. "I don't know exactly what it is that I can say to y'all. I was planning to rob this woman all along. It was all set up. There were no flaws that I could see. I just attempted to knock her unconscious. It didn't work. She didn't become unconscious. I just kept hitting her until she did."