STAFFORD COUNTY, Va. — In 2009, Jose Rodriguez-Cruz strangled his girlfriend, a 47-year-old federal worker, during an argument in her D.C. home and disposed of her still-missing body in such a calculated way that almost a decade passed before he was arrested and pleaded guilty to second-degree murder.

Now, amid a separate investigation arising from that 2009 case, Rodriguez-Cruz faces a new murder charge involving another vanished woman — this one in Virginia, where human bones found long ago on a highway median strip were identified last year as the remains of his estranged wife, last seen alive in 1989.

In announcing Friday that Rodriguez-Cruz, 54, has been indicted on a first-degree murder charge, Stafford County’s chief prosecutor, Eric L. Olsen, added fresh intrigue to the tortuous story of an ex-military police officer, a native of Puerto Rico, who authorities describe as explosively, homicidally violent, particularly toward women.

His 2009 victim, Pamela Butler, an IT specialist for the Environmental Protection Agency, had met Rodriguez-Cruz through an online dating service. After police finally arrested him, in 2017, he made a deal with D.C. prosecutors, agreeing to plead guilty to a reduced charge of second-degree murder and show detectives where he got rid of her body.

Butler’s family, though less than happy about the bargain, went along with it in hopes of recovering her remains. Rodriguez-Cruz, who was sentenced to 12 years in prison, led investigators to a spot along a highway in Stafford, but the area had since been dug up by construction crews, and her bones were not found.

Meanwhile, his involvement in Butler’s disappearance prompted Virginia authorities to revive a separate cold case, that of Marta Rodriguez, his missing estranged wife.

Remnants of a skeleton had been found in 1991 not far from where Rodriguez-Cruz said he dumped Butler’s corpse. Those bones, long held in storage, were tested last year, and DNA showed they were Marta Rodriguez’s, authorities said.

At a Friday news conference, Olsen said that since the identification of the remains, investigators have found evidence to warrant a first-degree murder indictment of Rodriguez-Cruz, who is serving his D.C. sentence in a federal prison. Olsen declined to discuss the evidence, but said Rodriguez-Cruz has not cooperated with detectives.

“I’m not sure he’s aware of what just occurred,” Olsen said of the new charge. It wasn’t immediately clear whether Rodriguez-Cruz has an attorney.

Butler’s brother, Derrick Butler, who said he now feels cheated by the D.C. plea deal because his sister’s remains haven’t been found, drove 50 miles from Washington to listen to Olsen’s announcement. Olsen said he has had “absolutely no” discussions about a plea bargain with Rodriguez-Cruz, which Derrick Butler said he was glad to hear.

First-degree murder in Virginia is punishable by 20 years to life behind bars.

“It’s still bittersweet for me,” Derrick Butler said. “No amount of [prison] time is going to bring my sister back, is going to bring Marta back.” But he added, “If that guy gets back out on the street, women out here are going to be in trouble.”

In January 2017, just before the ninth anniversary of Pamela Butler’s disappearance, a veteran D.C. homicide detective, Michael Fulton, took over the stalled case, in which Rodriguez-Cruz had been the prime suspect from the outset. New evidence gathered by Fulton led to the arrest in April that year of Rodriguez-Cruz, who was living in Alexandria at the time, and his subsequent plea bargain.

During his investigation, Fulton located a fresh witness who revealed previously unknown details about Rodriguez-Cruz, according to court affidavits.

The witness said that many years earlier, he had seen Rodriguez-Cruz hold a gun to the head of a woman to whom he had been married, an affidavit says. It says the witness also recalled seeing a letter that Rodriguez-Cruz had written, admitting he was “responsible” for the disappearance of that woman, now identified as Marta Rodriguez.

The witness who reported seeing the letter said he returned it to Rodriguez-Cruz “and never saw it again,” according to an affidavit.

Rodriguez, a 26-year-old nursing aide who lived in Arlington County, Va., was initially listed in county police files as a missing person in 1989. Then county police closed the case in 2001 after authorities in Florida said they had found a person they believed to be Rodriguez living in that state, an affidavit says.

The new information developed by Fulton led Arlington police to revive the missing-person case, and 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. That led county police to reopen the 1989 missing-person case.

Olsen said Friday that the identification of Rodriguez’s remains last year turned that investigation into “a hot” homicide probe, resulting in the new indictment.

Although Olsen declined to comment on any evidence, including how police think Marta Rodriguez died, it appears that authorities are unsure exactly where she was killed, in Arlington or Stafford. Under Virginia law in such cases, responsibility for prosecution rests with the jurisdiction where the victim’s remains were found, Olsen said.

Standing on the steps of a courthouse Friday, as Derrick Butler watched in a crowd of spectators, Olsen said, “We expect there’s going to be a jury trial here in Stafford.”