the unlikely intruder, the parker's family friend, bryan capnerhurst. riend bryan had shot his wife tammy in a botched robbery attempt. then brett, in fear for his own life, killed his friend. it looked like self-defense. but sheriff leon lott knew they couldn't close the case without thoroughly checking out brett's story. >> there were three people there and two of them were dead. we had to rely on him to explain to us what happened, so we listened to everything that he was saying and then we would go back and check it. >> investigators went over brett's account, starting with the moment bryan entered the house. before long, something unusual came to their attention. brett told police he was sitting on the downstairs toilet when he heard the shots ring out. but one of the female crime scene investigators notice this. the toilet seat was up. >> our csi lieutenant is a female, and she made mention of that because it particularly bothered her. >> of course, it takes a woman to notice that. >> right. >> as they poured over crime scene photos, another small