STAFFORD, Va. — A man imprisoned for killing a former girlfriend and federal worker in Washington a decade ago pleaded guilty Monday to slaying his estranged wife who disappeared from her Virginia home in 1989, authorities said.

Jose Angel Rodriguez-Cruz, 55, entered his plea to second-degree murder in Stafford Circuit Court, prosecutors said at a news conference.

Jose Rodriguez-Cruz was charged in October 2019 with killing Marta Haydee Rodriguez, then 28, the Commonwealth's Attorney for Stafford County said at the time. She was last seen in Arlington County 30 years ago.

Rodriguez's remains were found along a highway median in Stafford County in 1991, but they were not positively identified until DNA testing was used in 2018, news outlets reported, citing evidence presented by Stafford prosecutors.

Jose Rodriguez-Cruz said at the time that Rodriguez had left the country, and her remains weren't identified for years because the sister of Jose Rodriguez-Cruz's second wife had assumed her identity, authorities said. Police said they made the discovery in 2017.

By the time Rodriguez-Cruz was indicted, he was already serving a 12-year prison sentence for killing another woman, Pamela Butler, at her home in Washington in 2009, and also dumping her body in Stafford. The 47-year-old Environmental Protection Agency employee disappeared "under mysterious circumstances," authorities have said.

Butler's brother, Derrick Butler, encouraged Stafford authorities to pursue charges in the Rodriguez killing and is credited with being a key factor in the new charges.

"I'm very thankful that this has taken place," news outlets quoted Derrick Butler as saying Monday.

Commonwealth's Attorney Eric Olsen added that "a lot of agencies came together to bring justice to Marta Rodriguez, even if it is 30 years later."

Under Rodriguez–Cruz's plea agreement, a first-degree murder charge was reduced and a charge of concealing a dead body was dropped. He could face an additional 40 years in prison at a Feb. 4 sentencing, news outlets reported.