NEW YORK (AP) — For years prosecutors saw a connection in the killings of three young women who disappeared in the winter of 1993 and 1994, their nude bodies found strangled, beaten and left in similar poses in the Long Island brush.

In new charges unveiled Thursday, prosecutors said Rex Heuermann — the man already accused in a string of deaths known as the Gilgo Beach serial killings — was responsible for the death of one of the women, Sanda Costilla. The findings, authorities said, indicate that Heuermann began hunting victims more than a decade earlier than previously thought.

That in turn has raised questions about the conviction of another man, John Bittrolff, who is incarcerated for the murder of the other two women — Rita Tangredi and Colleen McNamee — and who prosecutors once considered a suspect in Costilla’s death.

Bittrolff’s lawyers have long accused prosecutors of relying on dubious forensics to convict him. They say the new charges against Heuermann cast further doubt on the case against their client, who has maintained his innocence since being sentenced to 50 years to life in 2017.

“You have three women killed in the same time frame and displayed in the same way, and now one is alleged to have been killed by Rex Heuermann,” said attorney Lisa Marcoccia of the Legal Aid Society, which is handling the appeal. “The evidence points to one killer, and the new indictment supports John Bittrolff’s claim of innocence.”

RELATED COVERAGE A timeline of the investigation of the Gilgo Beach killings Man charged in Gilgo Beach serial killings kept ‘blueprint’ of crimes on computer, prosecutors say Gilgo Beach serial killing suspect returning to court after a renewed search of his home

The trio of killings came roughly 16 years before the discovery of the remains of 10 people — mostly female sex workers — along a highway near Gilgo Beach on Long Island’s south shore. Heuermann, an architect, has pleaded not guilty to five of those killings and is considered a suspect in a sixth, in addition to Costilla’s death.

In the new indictment, prosecutors said forensic testing of hairs found on Costilla’s body determined they were likely Heuermann’s. The killing occurred shortly after Heuermann’s mother and another person moved out of his home, leaving him with “unfettered time to execute his plans,” prosecutors said.

Like the Gilgo Beach killings, those in the early 1990s stumped investigators for years. Then, in 2014, authorities caught a break: A DNA sample taken from Bittrolff’s brother proved a partial genetic match to semen found on the bodies of Tangredi and McNamee.

That led them to Bittrolff, a carpenter and father of two living in Manorville, on Long Island. His DNA was a full match.

Shortly after the arrest, Suffolk County District Attorney Thomas Spota speculated publicly that Bittrolff might have also been responsible for the death of Costilla, who disappeared weeks after Tangredi and two months before McNamee.

Though Bittrolff’s DNA was not found on Costilla, all three victims were displayed in the same sexual manner and missing a single shoe, prosecutors said, and wood shavings were found at all three scenes. Both Tangredi and McNamee were known to engage in sex work, while Costilla “led a similar lifestyle,” Spota said.

At the 2017 trial, Bittrolff’s lawyer conceded it was possible his client had sex with the two women but said that didn’t mean he killed them. Multiple sperm samples were found on the two women.

Prosecutors relied on the testimony of Suffolk County Medical Examiner Dr. Michael Caplan, who said he analyzed the density of the sperm to conclude Bittrolff had sex with them shortly before their deaths.

Defense lawyers did not call an expert to rebut that. But in an appeal motion, they cited DNA analyst and molecular biologist Dr. Karl Reich, who described sperm density analysis as “pure junk science.”

“Dr. Caplan’s testimony on a timeline since intercourse is not based on any scientific foundation,” Reich wrote in an affidavit, adding that such methods have “no precedent in forensic DNA practice.”

Jurors deliberated for seven days, repeatedly telling a judge they were deadlocked before eventually convicting Bittrolff. Afterward one said Caplan’s testimony was key to swaying undecided jurors, according to trial lawyer Jonathan Manley.

Spota credited the “miracle of DNA evidence” for catching and convicting Bittrolff.

Less than six months after the conviction, Spota was arrested for obstructing an investigation into the chief of the Suffolk County Police Department, who was accused of beating a prisoner. Both men were eventually convicted and sentenced to prison.

As with the Gilgo Beach investigation, the case against Bittrolff was dogged by allegations of mistakes and misconduct by police and prosecutors. During the trial, the Suffolk County police admitted to accidentally destroying the wood chips found on one of the women’s bodies and, separately, wood chips discovered in a car used by a police sergeant who was a potential suspect.

Police were also accused of prematurely destroying the sergeant’s investigative file. In their appeal, defense attorneys said prosecutors did not turn over another internal file containing allegations by the wife of a separate officer that her husband killed one of the women. Prosecutors maintain they did turn over that document; a judge has yet to rule.

John Ray, an attorney who has represented the families of some of the Gilgo Beach victims, said he had concerns about the case against Bittrolff from the beginning.

“There were huge defects in the presentation of the testimony, there was a question of incompetent counsel and the handling of the evidence was disgraceful,” he said. “Given what is now known, the prosecutors have an ethical duty to revisit and reexamine the Bittrolff case.”

Suffolk County Legislator Rob Trotta, a former detective on the FBI’s violent crime task force, agreed. “It’s worth another look,” he said. “Nothing would surprise me in this county.”

A spokesperson for the DA’s office did not respond to a request for comment. Outside court Thursday, an attorney for Heuermann, Michael Brown, said that his client was “obviously in a bad place in terms of the new charges.”

In the months before his arrest, court records show, Heuermann may have had an interest in the man whose high-profile murder charges proceeded his own. Among the hundreds of online searches that prosecutors say they found on his computer was a query that read: “John Bitroff.”