BOSTON (CBS/AP) — A convicted sex offender has been charged with killing a woman whose body was found in the basement of a Boston building more than three decades ago, according to Suffolk County District Attorney Rachael Rollins.

Richard Vega, 59, pleaded not guilty to a murder charge at his arraignment in Suffolk Superior Court Tuesday. He is already being held after a jury previously determined he was sexually dangerous.

Prosecutors say DNA evidence linked Vega to the 1988 killing of 21-year-old Judy Chamberlain, whose body was found in a building in what is now Boston’s Seaport neighborhood. Police found that she had been strangled and sexually assaulted.

Judy Chamberlain. (Photo credit: Suffolk County District Attorney )

Vega was identified as a suspect in 2011 after a federal database matched his DNA profile to evidence from the 1988 killing, according to Rollins’ office, but prosecutors at the time did not think they had enough evidence to bring charges.

Vega had been required to submit a DNA sample after he was convicted of rape in a 1987 attack on an elderly woman in Revere.

Vega was sentenced to up to 20 years in prison for the 1987 attack, and a jury in 2008 found that he was sexually dangerous and should remain at a corrections facility.

Investigators recently collected new evidence in the case allowing them to bring the case to a Suffolk County grand jury, prosecutors said. A jury returned an indictment Aug. 30 charging Vega with Chamberlain’s murder.

Richard Vega in Suffolk Superior Court, Oct. 26, 2021. (WBZ-TV)

“Ms. Chamberlain’s family has been waiting 33 years for answers,” Rollins said in a statement. “We were finally able to offer those answers some three decades later. Ms. Chamberlain’s life mattered.”

Vega is due back in court November 30.

The investigation got fresh attention from authorities as part of a recent effort to solve Boston-area cold cases dating to the 1960s. Rollins started the initiative, known as the Project for Unsolved Suffolk Homicides, when she took office in 2019.

The effort has led to murder indictments in two other killings, from 1995 and 1980, according to the district attorney’s office.

(© Copyright 2021 CBS Broadcasting Inc. All Rights Reserved. The Associated Press contributed to this report.)