The Green River Killer
The murders first started in Kings County Washington. The operation to catch the perpetrator was lead by the Kings County Sheriffs Department and the special Green River Task Force that was put on the case. Robert Keppel was at the head of the investigation, even going to interview Ted Bundy to find out what kind of murderer they were dealing with. Most of the bodies still had semen samples that were taken throughout the years, and other than that there was only so much they could do at the time without DNA identification.
The Department was criticized because of the loss of some of the evidence throughout the investigation, usually by mistake or overload of victims they were dealing with.
http://www.vanishedvoices.com/RewardPoster.jpg
At one point the Police interviewed Ridgeway in connection with the case but had no evidence to charge him, they did however take a sample of his DNA. When DNA comparison finally became available to the investigation they tested multiple DNA samples which came back to match Ridgeway. Ridgeway still admitted to nothing, until the final straw came in 2002. Tiny spheres of paint were found at multiple crime scenes all the same type of paint, which was the same paint that was used at the body shop that Ridgeway worked at. The two paint samples were compared and were a match. Ridgeway pleaded guilty to over 40 of the murders in exchange for not receiving the death penalty.