when police interviewed david nixon's live-in girlfriend, tracey frame, she claimed david was headed to las vegas on the night he disappeared. tracey also revealed she didn't have an alibi for the night david was murdered. she said she was at home alone. >> we, as a family, didn't really know much of anything. he didn't bring her up. i never spoke to her on the phone. she was a mystery to all of us really. >> a background check revealed the two had an interesting past. the couple met at a lake party shortly after david's second wife left him. tracey was a successful accountant with no children. shortly after they got together, david bought two matching cars, a black lexus for tracey, a white one for him.