Ridgway already confessed to killing Rebecca "Becky" Marrero, a 20-year-old mother and prostitute last seen when she left a motel in 1982. But prosecutors declined to include her case in a 2003 plea deal that spared Ridgway the death penalty, because he was not able to provide conclusive evidence that he killed her.
The plea deal required Ridgway to plead guilty to future King County charges based on new evidence, and he is expected to do so on Feb. 18 at the Regional Justice Center in Kent. Marrero's family will have the opportunity to confront him.
"They always thought maybe he had killed her but they didn't know for sure," said King County Prosecutor Dan Satterberg. "It's important for the family to be able to have the answers."
Ridgway, a commercial truck painter, is one of the nation's most prolific serial killers, having been convicted of 48 murders and having confessed to or been suspected of dozens more. He preyed upon women and girls at the margins of society - runaways, prostitutes and drug addicts strangled in a spree that terrorized Seattle and its south suburbs in the 1980s. Several victims were dumped in or posed along the Green River.
Ridgway was arrested in 2001 after advances in DNA technology enabled authorities to link a saliva sample he gave authorities in 1987 to some of the bodies. He pleaded guilty two years later, agreeing to help authorities locate as many remains as possible.
He is serving life without release in solitary confinement at the state prison in Walla Walla, where he's allowed out of his cell one hour a day four times a week.
Ridgway's lawyer, Mark Prothero, confirmed that he expects Ridgway to plead guilty.
"He acknowledged he killed her back in 2003," Prothero said. "He was glad they were able to find more remains and hopes they'll be more successful finding others as time goes on. He's prepared to accept responsibility."
Marrero's remains were found Dec. 21 in an Auburn ravine, 100 feet from where investigators found another of Ridgway's victims, Marie Malvar, in 2003. The Marrero family recently gave her a proper burial, Satterberg said.