for five years, the murder of pat mcrae went unsolved. investigators had the dna profile of the killer and boot impressions from the scene. what they didn't have was a viable suspect. >> i just kind of gave up worrying about whether or not it would get solved. i mean, i didn't like that it wouldn't, but i had that feeling that there was probably nothing we could do. >> then detective judy stanley got a call from her counterpart in lincoln, nebraska, 200 miles away. lincoln police had just arrested a man named mars davis on a drug possession charge, and davis offered them a deal. he said he was willing to provide information about an unsolved murder in des moines in return for leniency on his drug charge. >> i felt tremendously guilty for a long time. i didn't want to think about it