If it's true, Ridgway's plea deal that allowed him to escape the death penalty in Washington state wouldn't protect him.
Oregon detectives have released the names of two men they want to talk to. They hope the men can tie Ridgway to the murder of an Oregon girl.
"It's been a long time. It's been an awful long time," said Randy Girdner, whose daughter was murdered decades ago.
But now, Randy and Reta Girdner have some answers. The remains of their daughter, Angela Girdner, have been found at an Oregon medical examiner's office, where they'd gotten lost nearly 25 years ago.
"This is one of the worst things that can happen to a parent...is the torture of continually looking for your daughter," said Randy Girdner.
The Girdners now have their daughter's bones, but not her killer. They're convinced it's the Green River Killer, or Gary Ridgway.
Angela Girdner's remains were found in 1985 along a road in Tualitan, Oregon, and not far from the remains of Denise Bush and Shirley Sherill, who are both victims of Ridgway.
In 2003, Ridgway confessed to killing Bush, Sherill and 46 others in a deal to avoid the death penalty. He even guided the Green River Killer Task Force into Oregon to the place where he'd dumped their bones.
But Ridgway never confessed to killing Angela Girdner. Washington County Det. Ray Marcom is convinced Ridgway refuses, because his plea bargain only protects him from the death penalty in Washington state. If Angela Girdner died in Oregon, Ridgway could face the death penalty there.
"I believe she died in Oregon," Marcom said. "I have not found any evidence to show that she was ever in Washington state."
Marcom says one man - Charles William Wakefield, III - could be crucial to tying Ridgway to Angela Girdner's death. Wakefield was just 18 when the victim met him in 1983.
"She was friendly, and fell in love at the age of 15 to find out that the fellow she fell in love with was a pimp," said mother Reta Girdner.
Investigators say Wakefield pulled Angela Girdner into prostitution.
"I can't talk about why, but I believe he's in this area," said Marcom, who is convinced Wakefield can help retrace Angela Girdner's steps, and possibly finger Ridgway as the man who picked her up.
"It seems like all the evidence and everything is right down the line with what he's done before," said Randy Girdner. "Yeah, I'm convinced."
Ridgway's lawyers are convinced he told investigators all he knows, and that he has no other victims. Still, investigators in Oregon are pressing on, looking to fill in the blanks that Gary Ridgway can't, or won't.