>> did it make you think that maybe he could have been behind this? >> this made me have a lot of questions. >> while any case against darin would have been purely circumstantial, that didn't explain why doug mulder hadn't fended off some of the circumstantial evidence against darlie who was facing death row. >> really the biggest failure was the failure to use any forensic testing to advance the defense on darlie's behalf. >> the primary evidence, i think, was probably the strongest forensic evidence that the state had. >> the state contended that fibers found on a bread knife in the routiers' kitchen matched the slashed window screen. >> they didn't do any testing to exclude any other sources for that fiber or to pin it down to