A man who admitted strangling his girlfriend in the District in 2009, and then disposing of her still-missing body, pleaded guilty Monday to the 1989 murder of his estranged wife, whose remains were hidden along a highway median strip.

Appearing in a Stafford County, Va., courtroom, Jose Rodriguez-Cruz, 55, pleaded guilty to second-degree murder in the death of Marta Rodriguez, 26, a nursing aide who was last seen alive May 25, 1989. Her skeletal remains, found in Stafford in 1991, were not identified until 2018.

The guilty plea follows a pair of tortuous, related investigations in the District and Virginia that stretched for years, involving two missing victims, multiple police departments and a suspect described by authorities as having an explosive, homicidal temper toward women who spurned him.

In Virginia, second-degree murder is punishable by five to 40 years in prison. No sentencing date has been set for Rodriguez-Cruz.

About a decade after Marta Rodriguez’s 1989 disappearance from Arlington County, Rodriguez-Cruz became romantically involved with a D.C. woman, Pamela Butler, a 47-year-old computer specialist for the Environmental Protection Agency. In February 2009, she also mysteriously vanished.

Although Butler’s body has not been found, Rodriguez-Cruz, a clerical worker at a substance abuse clinic who had lived in Northern Virginia, was arrested in 2017 by D.C. police in a case built almost entirely on circumstantial evidence. He eventually admitted in court that he had strangled her.

Her family said she was in the process of breaking up with him when she disappeared.

In a deal with prosecutors in the Butler case, Rodriguez-Cruz was allowed to plead guilty to a reduced charge of second-degree murder and got just 12 years in prison, in return for agreeing to help police recover her body. He led them to a spot along Interstate 95 in Stafford, but the area had since been dug up for construction, and Butler’s bones were gone.

“At the time authorities were searching I-95 for Butler’s remains, the Virginia State Police investigators who were assisting the D.C. authorities alerted their fellow officers . . . that unidentified remains had been located near the same location” in 1991, long before Butler’s disappearance, Stafford Commonwealth’s Attorney Eric L. Olsen said Monday.

This caused investigators to suspect that the bones found in 1991, still held in storage, were those of Rodriguez-Cruz’s missing wife. After DNA tests confirmed the suspicion, Rodriguez-Cruz was charged in October 2019 with first-degree murder in her death.

An autopsy report lists the cause and manner of Marta Rodriguez’s death as undetermined. Prosecutors have not said publicly whether Rodriguez-Cruz has described to them how she died.

In March 1989, two months before Marta Rodriguez vanished, Rodriguez-Cruz, a former military police officer, was charged with abducting and assaulting her. In that incident, an Arlington County police officer saw him dragging her along a street, bound and gagged, authorities said.

“When asked by the investigator why he would commit such acts against his wife, Rodriguez-Cruz responded that ‘if I can’t have her, no one else will. She’s mine,’ ” according to a statement issued Monday by Olsen’s office.

However, the case against him began to fall apart on May 18, 1989, when Marta Rodriguez failed to appear in an Arlington courtroom for a preliminary hearing. “It is unclear whether she stayed away of her own accord or whether she was kept away,” the statement said. “Regardless, she would live for only one more week.”

Marta Rodriguez was initially listed in Arlington County police files as a missing person. County police closed that case in 2001 after authorities in Florida said they had found a person they believed to be Marta Rodriguez living in that state. It turned out that the woman living in Florida under Marta Rodriguez’s name was an acquaintance of Rodriguez-Cruz who was falsely using her identify, authorities said.

After Rodriguez-Cruz’s 2017 plea bargain in the Butler case, Butler’s family members said they were less than pleased with his relatively light sentence of 12 years. But they said they went along with it in hopes of recovering her remains, before those hopes were dashed.

Her brother, Derrick Butler, who attended Monday’s court hearing in Stafford, said in an interview that he was satisfied with the latest plea bargain. He said Olsen told him he is confident that Rodriguez-Cruz’s eventual sentence will be at “the high end” of the five-to-40-year punishment range.

“Yes, I’m happy — indeed I am,” Butler said. “It feels good to finally be done with this.”