Gilgo Beach Serial-Murder Case Hangs on a Hair and Its DNA

After 13 years of dead ends and blown leads, the Gilgo Beach murder investigation finally turned on pizza crusts that Rex Heuermann had tossed in a trash can in Midtown Manhattan.

It was a jackpot for investigators who had watched Mr. Heuermann for months.

“Pizza crust is like a sponge — it allowed the saliva to seep into the dough,” Ray Tierney, the Suffolk County district attorney, said in a recent interview.

The sample gave investigators the genetic match that helped connect Mr. Heuermann to four bodies found in 2010 on Long Island, and his arrest followed in July, Mr. Tierney said. When Mr. Heuermann’s trial begins, possibly this year, the DNA evidence will underpin the charges that he murdered women he had hired as escorts and left their bodies wrapped in burlap along a desolate oceanfront parkway.

Investigators say the DNA profile obtained from a male hair found on the burlap used to wrap one of the four victims found in 2010, Megan Waterman, corresponds to the pizza slice sample from Mr. Heuermann.

The authorities have charged Mr. Heuermann with three of the killings, but refrained from a fourth charge because genetic test results were incomplete in July. Mr. Heuermann has pleaded not guilty and is being held without bail at a Suffolk County jail.

Prosecutors have said Mr. Heuermann will likely be charged this month in connection with the fourth body, and on Monday morning they announced he would appear in court in Riverhead on Tuesday, with prosecutors holding a news conference afterward.

Mr. Tierney, who plans on arguing the case himself, said the DNA evidence made the case a strong one.

But to Mr. Heuermann’s lawyer, Michael J. Brown, a withered strand of hair — the only physical evidence purporting to link his client to any of the bodies — is a flimsy clue on which to hang a case.

And genetic experts say Mr. Brown will try to sow doubt among jurors about the DNA evidence.

This could include challenging the constitutionality of obtaining the pizza sample and scrutinizing every aspect of the genetic specimens’ collection, transport and testing, said Steve Mercer, a Maryland lawyer who serves as an expert witness and consultant for defense attorneys in forensic DNA cases.

Mr. Mercer said the defense might also look into the record of the forensic labs that investigators used and tell jurors that the genetic evidence “doesn’t establish what happened.”

“You’re talking about a piece of hair that doesn’t reveal any activity or even a connection to the murder itself,” he said. “The evidence itself doesn’t tell you how it got there.”

Presenting complex evidence to a jurors can be a challenge, said Lawrence Kobilinsky, a forensic science consultant.

“It’s never, ever a slam-dunk case with DNA evidence, because you can never be sure of how a jury reacts,” he said. “I’ve given trial testimony in cases where I look over and see jurors nodding out.”

Mr. Brown did not reply to a request for comment, but at a recent court conference he took issue with the mitochondrial DNA testing used by prosecutors, which does not prove a link to a specific person but rather narrows down matches by ruling out most other people. It is helpful when nuclear DNA is severely degraded, as it was in this case.

Prosecutors say that while 99.96 percent of the population is excluded as a match for the Waterman hair, Mr. Heuermann cannot be, based on his genetic profile from the DNA on the pizza and a court-ordered swab after his arrest.

Mr. Brown countered that this still allows for “thousands and thousands” of men on Long Island alone whose DNA could correspond to the Waterman hair.

Mitochondrial DNA tests on other hair strands found on the victims indicate that they came from Mr. Heuermann’s wife, Asa Ellerup, which leaves little doubt of Mr. Heuermann’s involvement, Mr. Tierney said.

Prosecutors say Ms. Ellerup, who has not been charged, was on vacation when the victims disappeared but that her husband probably inadvertently carried her hair from home onto his victims, perhaps on a roll of tape used to bind the bodies.

The victims — Ms. Waterman, Amber Costello, Melissa Barthelemy and Maureen Brainard-Barnes, known as the Gilgo Four — were the first of 10 people whose remains would ultimately be found along Ocean Parkway in 2010 and 2011. The other six deaths are still being investigated.

The young women who made up the Gilgo Four were all working as escorts and had gone missing after meeting a client who contacted them with disposable cellphones.

They were identified by their own DNA early on, but stray hairs found on each did not offer immediate clues. The hairs, exposed for months or years to the raw elements on windswept oceanfront terrain, were so decomposed that it was impossible to conduct the nuclear DNA analysis that identifies suspects in genetic databases.

When in March 2022 Mr. Heuermann was identified as a suspect, it was not through DNA but rather a decade-old tip regarding his distinctive pickup truck.

Investigators quickly had enough circumstantial evidence to convince them Mr. Heuermann was their man, including mobile phone location records connecting him to the four victims at the time of their disappearance. They also discovered his internet history of using burner phones to browse sadistic pornography and escort sites, Mr. Tierney said.

But to secure an indictment, they needed to assemble a solid genetic case using mitochondrial DNA analysis. For this they would need to obtain surreptitious samples from Mr. Heuermann and his family.

“You don’t arrest someone on a wing and a prayer, much less the biggest case in Suffolk County,” Mr. Tierney said.

In fact, the DNA evidence was so crucial that it led investigators to allow Mr. Heuermann to remain free more than a year so they could gather it. They worried that perhaps he might kill again or get tipped off that he was a suspect. The task force set up surveillance teams to tail Mr. Heuermann and installed cameras outside his home.

In July 2022, an outside forensics laboratory that used techniques including direct genome sequencing confirmed investigators’ suspicions that the hairs found on Ms. Barnes, Ms. Waterman and Ms. Costello were indeed female hairs that had not belonged to the victims.

That same month, an undercover detective plucked empty bottles from a recycling pail outside Mr. Heuermann’s dilapidated Massapequa Park home.

Now investigators could use the bottle samples to create genetic profiles on Ms. Ellerup, Mr. Heuermann and their two grown children. But they still wanted a direct genetic sample from Mr. Heuermann.

As months went by, the more they learned about Mr. Heuermann, the more tension heightened among task force officials over whether to arrest him.

He was using burner phones and fake identities to access his Tinder account, contact massage parlors and escorts and keep up on the investigation. Also, as an avid hunter with more than 90 gun permits, he seemed to have an arsenal of weapons at home.

“Our surveillance could have been detected, or he could have engaged in activity that would give us pause,” Mr. Tierney said. “So it was tough.”

There were also worries about leaks. This task force began as a trusted core of mostly law enforcement officials and maintained a tight ring of secrecy for more than a year, Mr. Tierney said. By the spring of 2023, “every day, that expanded,” said Mr. Tierney, as more people were needed to tail Mr. Heuermann. Hundreds of subpoenas were issued, and finally witnesses began testifying in front of a grand jury.

By June 2023, the genetic tests on the bottles and the pizza slice DNA positively linked Mr. Heuermann and his wife to the bodies, and a grand jury was convened.

Prosecutors were anxiously awaiting lab results linking Mr. Heuermann to Ms. Brainard Barnes. But hearing rumblings of a possible media leak regarding Mr. Heuermann, they decided to arrest him immediately and charge him with three murders.

Mr. Tierney said there had been an elaborate puzzle to assemble.

“The reason no arrest was made on this case for 13 years is because there were no eyewitnesses,” he said. “You have to look at all the available evidence and evaluate it all and piece it together.”

But Mr. Mercer said that because the genetic samples were collected more than a dozen years ago and because the investigation took a winding path, “the defense will have quite a bit to work with to provide a counternarrative.”