Transcript for Green River Killer Claims Dozens More Victims
When Gary came here in the eighties when -- put the body here there -- this used to be erode that went straight in. -- FitzGerald is a man with a mission if this was a road right here. He's a former air force criminal investigator with multiple accommodations for counterterrorism. Operations and solving high profile crimes. Now in the private sector he no longer has a batch but he still -- investigator at heart. So he's turned his focus to one of our area's most notorious cases. Gary Ridgway the Green River killer -- for bone fragments and we're looking for charcoal. And what he's looking for are the remains of two women -- allegedly killed and that -- bodies have never been found. Nobody's doing this which was kind of a shocking thing. How these victims' families are out there and my whole goal all along has been doing -- one of these family members but their daughter. -- back and forth -- couldn't. And that it children. In 2003. Ridgeway confessed to strangling dozens of women and dumping their bodies in forested and rural areas around King County. He's serving -- 49 life sentences for 49 murdered women. He was suspected of many more but the bodies of those women have never been found. And these are the ones we have not found it. He says are still out there. FitzGerald has become an expert on the Green River murders at least twice gone through every tape king county sheriff's investigators recorded of their -- interviews. He's read everything ever written on the case and a few years ago he started talking regularly -- Ridgeway mostly by phone. Com more news radio reporter Charlie -- began taping these exclusive conversations. After Ridgway agreed to talk on the record. And FitzGerald uses the contacts to fill in -- only a killer would know. Well like children back from a truck in the inning parking -- restaurant pock marks. Having Ridgeway identify locations on maps. Well I think -- -- place that it would 2000 killer most likely. Looking for clues on -- to concentrate -- search but that the maps talking with Gary puts it all together becomes -- one. This is the same process sheriff's detectives used in 2003. It was a condition for Ridgeway to avoid the death penalty. Those interviews and searches led to the remains of four more victims. That was ten years ago. Since then the economy's tanked shutting down the sheriff's cold case squad. When the decimated for the Great Recession sheriff's office of the decimated. And with no new clues they haven't searched for Green River remains in years this is not to say that. Cold cases don't get investigated. But only if we get a new -- her cart is skeptical of anyone hoping to sift out truth from Ridgeway. Is he lying. Idea for Fred and sell lot of it -- lies -- -- -- lies FitzGerald says he's aware -- could be playing him and adds those conversations. Are just a piece of the puzzle but if there's little nuggets of truth in there that's what I'm really after. So FitzGerald -- his team of volunteers use every summer weekend to search every location that looks promising. He sifted through literally tons of dirt and rocks. And looking for anything that doesn't fifth. He has a plastic skeleton to compare possible bone fragments could. Good girl he has a Bloodhound Wendy trained to search for cadavers and a van full of forensic equipment. Because FitzGerald is a man plagued by a case without answers. Families still wondering what happened to their loved ones but -- I don't do it nobody's doing it's nobody's doing a bill. And nobody will.
This transcript has been automatically generated and may not be 100% accurate.