Green River Killer Gary Ridgway will be charged with the murder of a woman whose remains were found in December down a steep ravine in west Auburn, King County Prosecutor Dan Satterberg said in a news conference Monday.

The charge will be the serial killer’s 49th count of first-degree aggravated murder.

On Dec. 21, three teenagers playing in a wooded ravine on Auburn’s West Hill spotted a moss-covered skull under a log and notified authorities. The remains were later identified as those of Becky Marrero, a 20-year-old woman whom detectives believed was one of Ridgway’s early victims.

The original Green River Task Force list of 49 possible victims in the 1980s numbered Marrero among several missing women.

Ridgway, who is already serving a life sentence for murdering 48 women, will be formally arraigned at 1:30 p.m., Feb. 18 at the Norm Maleng Justice Center in Kent.

“The Marreros have the right to face the man who killed Becky and the opportunity to remind us all about what was taken from them,” Satterberg said. “They finally have answers and with these charges and the anticipated guilty plea, they will have obtained the truth, accountability, and they will have achieved a degree of justice for Becky Marrero.”

Ridgway will be transported from his Washington State Penitentiary cell in Walla Walla to the hearing, where he is expected to plead guilty “pursuant to the original (2003) plea agreement,” then brought back to his cell, Satterberg said.

Attorney Mark Prothero, who co-led Ridgway’s defense team, has been assigned to represent him, Satterberg said.

“It will be relatively quick, it will be relatively inexpensive,” Satterberg said of the arraignment. “By the time we get done with this, it will be one of the cheapest aggravated murder convictions in country history.”

In a plea agreement made by late King County Prosecutor Norm Maleng in 2003, Ridgway agreed to plead guilty to any future cases in which his confession could be corroborated with reliable evidence uncovered by investigators. In return, Ridgway was spared the death penalty.

“This is not a death penalty case,” Satterberg reinterated, “because it falls squarely within the agreement made in 2003. Seeking the death penalty in this case not only would be difficult, it would be impossible.”

Satterberg said if Ridgway does not plead guilty, he would breach the plea deal, jeopardizing his standing and potentially lead to the death penalty.

Satterberg indicated that Ridgway’s defense team will render a guilty plea to the latest charge.

Ridgway faces another life-term sentence. He is serving 48 consecutive life terms for his murders.

The Sheriff’s Office questioned a cooperative Ridgway in 2003 about Marrero’s disappearance. Though Ridgway had confessed to killing Marerro in 2003, Satterberg said, her remains had not been found and Ridgway was unable to provide sufficient details to charge him with her murder.

“He provided few details,” Satterberg said of the Marrero investigation.

After finding Marrero’s body, investigators said they finally had the evidence needed to charge Ridgway with Marrero’s death.

Marrero, 20 at the time, was last seen on Dec. 3, 1982 when she left a motel room at South 168th and Pacific Highway South. She had left her 3-year-old daughter with her grandmother and was only to be gone a short while. Her family never heard from her again. Her mother reported her missing to the Sheriff’s Office on July 20, 1984.

The remains of Marie Malvar were found Sept. 28, 2003 in the same general area where Marrero was found. Malvar was last seen in 1983 at South 216th and Pacific Highway South. Ridgway was convicted in the Malvar homicide and was questioned extensively in 2003 about Marrero’s disappearance. The Sheriff’s Office, however, says policy does not allow it to discuss what suspects say or don’t say during the investigation of open cases.

Satterberg said there likely are more remains of victims still missing, but efforts remain focused on achieving closure for the victims’ families.

Satterberg said the family was able to give Marrero family a proper burial following church services last Saturday.