dawn had another neighbor, robert knight, who had some prior arrests for drug possession. >> robert knightade comments to the victim as she was outside washing her car or going to and from her automobile to her apartment. this subject would make comments to her in a sexual suggestive nature, and he became a suspect. >> robert knight had type "a" blood consistent with the semen sample from the crime scene, but he had an alibi for the night of the murder. he said he was with his girlfriend at the time, and the fingerprint on the pillowcase did not appear to match the fingerprints on file for robert knight. >> we tried traditional photography, everything that we knew at that point in time also, to develop some contrast between the ridges and the fabric. but basically, those techniques were not satisfactory at that point in time. we couldn't get it to a point where we felt like we had an identifiable print. >> scientists tried various chemical processes to improve the print on the pillowcase. but every time they enhanced it, they also enhanced the threads of the pillowcase. investigators were