Virginia authorities confirmed Wednesday that newly identified skeletal remains are those of an Arlington woman missing since 1989, whose ex-husband pleaded guilty to killing his onetime girlfriend in the District 20 years later.

Marta Haydee Rodriguez, a 28-year-old nurse’s aide, disappeared after work. She was last seen walking to a bus stop.

“Charges are pending at this time” in Rodriguez’s case, Virginia State Police said in a statement, and the investigation is ongoing.

The remains were discovered in 1991 in Stafford County but had long remained a mystery. Authorities said they conducted new DNA testing of the remains, which led to the identification, after evidence emerged in the D.C. case.

Rodriguez’s former husband, Jose Rodriguez-Cruz, was charged in 2017 in the District with the murder of his onetime girlfriend. Pamela Butler, of Northwest Washington, went missing in 2009. Her body has never been found.

Rodriguez-Cruz, now 52, last year pleaded guilty to second-degree murder, admitting in court that he strangled the 47-year-old computer analyst to death and dumped her body in Virginia.

Marta Haydee Rodriguez went missing in 1989. Authorities concluded that remains found in 1991 in Stafford County, Va., were those of Rodriguez. (N/A/Family photo)

As part of the plea deal, Rodriguez-Cruz was sentenced to 12 years in prison in exchange for helping authorities locate Butler’s remains. But authorities ultimately determined that the once-wooded area where Rodriguez-Cruz said he dumped Butler’s body has since been paved as part of the resurfacing of I-95.

That area is about a mile from where Rodriguez’s remains were found on Feb. 3, 1991, in a median area along the interstate.

Judith Pipe, Rodriguez-Cruz’s D.C. public defender, declined to comment on the Virginia developments.

D.C. homicide detectives and prosecutors have said in court that they believed Rodriguez-Cruz was responsible for his wife’s disappearance.

During a D.C. Superior Court hearing in 2017, authorities described what they said was Rodriguez-Cruz’s pattern of violent behavior toward women.

Michael Fulton, a D.C. homicide detective, testified that a newly discovered witness told detectives that 22 years ago he had found a letter Rodriguez-Cruz wrote, saying he was “responsible” for his wife’s disappearance. The witness told police that he returned the letter to Rodriguez-Cruz and did not see it again. The witness also said that he once watched Rodriguez-Cruz hold a gun to another woman’s head as she begged for her life.

Court documents also describe a tumultuous relationship between the two.

In one instance in March 1989, Rodriguez-Cruz was accused of abducting Rodriguez, binding her with rope and duct tape, and driving her to a motel, court papers show. Rodriguez-Cruz was criminally charged, but the case was dismissed when Rodriguez failed to show up in court.

Police said she was reported missing a week later by a roommate in Arlington.

Deborah Sines, who in April retired as an assistant U.S. attorney for the District and who started investigating the Butler case in 2013, said the two women’s cases are intertwined.

“Marta was always part of it. You couldn’t investigate Pam without investigating Marta,” Sines said.

“I’m relieved that they identified her and that they opened a case,” Sines said. “I am hoping this will give the family some comfort.”

Paul Duggan contributed to this report.