ridgway to chew on a piece of gauze to leave them a sample of his saliva, his dna. it was just a tiny amount but that was all they were legally allowed to get. of course, back then the science of dna was in its infancy. so investigators simply stored it in the evidence freezer, along with what they had on other suspects. >> we got to a point where there was nothing else we could do. >> one more thing argued against ridgway and other suspects. there seemed to be a reprieve from the terror. it had been three years since a prostitute disappeared from the sea-tac strip. had the green river killer disappeared, too? the original profile said this is a serial killer, he's going to keep killing, and all of a sudden the killing stopped. or they appeared to. >> right. >> so you guys logically assume the guy is either in jail, he's dead or he's left. >> we never grabbed onto any one