On February 18, 2011, in a Kent, Washington, courtroom, Gary Leon Ridgway pleads guilty to the 1982 aggravated, first-degree murder of his 49th victim, 20-year-old Rebecca Marrero.

Marrero’s remains were found in December 2010, decades after her murder, in a ravine near Auburn, Washington. After entering his guilty plea, the 62-year-old Ridgway received his 49th life sentence without the possibility of parole and returned to the Washington State Penitentiary in Walla Walla, where he was already serving 48 consecutive life sentences, one for each of the other women he killed.

In the 1980s, residents of Washington State were terrorized by the so-called Green River Killer, whose first five victims’ bodies were discovered in or near the Green River in King County (whose largest city is Seattle) in the summer of 1982. The strangled bodies of more victims soon appeared around King County; all were women, most of them young and many of them prostitutes, runaways and drug users.

Ridgway, a thrice-married truck painter from Auburn, became a suspect after one of the victims was spotted getting into his truck. However, when questioned by police, he denied any knowledge of the slayings and passed a 1984 polygraph test. In 2001, he was finally arrested after DNA evidence (a technology not available when he began committing his crimes) connected him to some of the killings.

In a controversial 2003 plea deal, Ridgway admitted to the murders of 48 women between 1982 and 1998, and prosecutors agreed not to seek the death penalty against him if he cooperated with police in locating the remains of dozens of his victims. Ridgway reportedly claimed to have murdered more than 60 women in King County, although authorities at the time could only find sufficient evidence to link him to the 48 slayings; later he was convicted of a 49th.

Ridgway told authorities he began to think of murdering prostitutes as his career, and did it “because he hated them, didn’t want to pay them for sex, and because he knew he could kill as many as he wanted without getting caught,” according to The Seattle Times. The serial killer said he picked up women off the street, strangled them in his home or truck, and meticulously hid their bodies near natural landmarks (such as trees or fallen logs) in an attempt to keep track of them.