what kind of system is that? >> while duckett's appeal was severely weakened without gurley's recanted testimony, beth wells was still able to attack the prosecution's case, starting with the tire tracks found near teresa's body. >> the little dirt road had the tire tracks by it, which was a pretty good find by the detective. they preserved the tracks, did a mold of it, everything else. sure enough the tire tracks had the same tread pattern that the police cars had. but just because somebody had the tire tread with the same basic pattern doesn't mean it was that car. >> duckett's former boss, police chief michael brady was also suspicious of the evidence. soon after the investigators left the crime scene, he made a discovery that convinced him the evidence was flawed. >> we went out and could find no evidence that the investigators had lifted any kind of tire