Gilgo Beach serial killer: How task force built case against Rex Heuermann

The evidence in the Gilgo Beach killings was vast and, at first, potentially useless in court.

To make the case stick, investigators would have to rebuild it from the ground up, turning years of scattered leads into a single, prosecutable story that was admissible in court.

When Suffolk County’s new district attorney, Raymond Tierney, first reviewed the case in early 2022, he quickly grasped the problem. Detectives and analysts had amassed troves of information — including intricate cellphone data mapping connections between suspects and victims — but there was no clear path to introduce much of it as evidence at trial.

“It got ugly really, really fast,” Tierney said in an interview, recalling his first briefing on the investigation. “I said, ‘Great, how are we getting this into evidence?’ And everybody just looked at each other.”

The distinction was crucial. Gathering evidence is one thing. Making it admissible, and persuasive to a jury, is another. In the Gilgo case, that gap threatened to undermine more than a decade of work.

Tierney left the meeting angry, he said, convinced that without a fundamental reset, the investigation risked collapsing under its own weight.

He turned to a recently hired chief investigator, Richard Zacarese, a soft-spoken former New York Police Department lieutenant with a reputation for untangling complex cases.

Zacarese, 49, had spent years refining a method in gang prosecutions: build sprawling, multidefendant cases by weaving together disparate crimes into a single narrative, supported by legally sound evidence at every step. It was a meticulous, methodical approach, and one that had not been fully applied to the Gilgo investigation.

Now, it would become the blueprint.

Working with a newly formed task force that eventually spanned 17 law enforcement agencies, Zacarese took on what colleagues describe as a sweeping overhaul. Evidence collected over more than a decade — phone records, witness accounts, forensic findings — had to be reexamined, restructured and, in some cases, reobtained to ensure it could withstand legal scrutiny.

From the outset, the focus shifted. Investigators were no longer simply gathering information; they were building a case that could be told, step by step, in a courtroom.

“It was about making sure every piece fit,” Zacarese said. “Not just what we had — but how we got it, and how we were going to use it.”

Within weeks, the retooled approach began to sharpen the investigation. By the spring of 2022, the task force had zeroed in on a suspect: Rex A. Heuermann, a Massapequa Park architect whose movements, vehicles and phone activity began to align with the timeline of the killing.

Tierney, Zacarese and assistant district attorneys Nick Santomartino and Andrew Lee spoke with Newsday exclusively about the early, sometimes tense and all-consuming days of the Gilgo Beach probe. Tierney and former Suffolk Police Commissioner Rodney K. Harrison agreed that a task force approach was what they needed to jump start the investigation and get the case ready for a trial unlike any Long Island had seen before.

The prosecutorial team ended up with evidence so strong and overwhelming that Heuermann, 62, who was indicted on murder charges in the killing of seven Gilgo victims — Amber Lynn Costello, Megan Waterman, Maureen Brainard-Barnes, Jessica Taylor, Valerie Mack, Sandra Costilla and Melissa Barthelemy — pleaded guilty on April 8 to the strangulation homicides. Heuermann also admitted as part of his plea to killing Karen Vergata,  although he wasn’t charged with that crime. He is scheduled to be sentenced on June 17 to life terms in prison.

Phone records and vehicle description

Ultimately, the telephone records Tierney had found so problematic in the beginning of the probe turned out to be a linchpin in the Gilgo case. Heuermann’s personal phone and his burner phones sometimes moved in close geographic proximity to the phones of the dead women, investigators determined.

“After we got back the Verizon phone records, we were able to start matching them up. It was then we said this looks like this could definitely be the guy,” Zacarese said. “Then we started filling in all the additional warrants and all of the building blocks from that point forward.”

By March 2022, just a few weeks after the task force was formed, Zacarese and others on the task force had zeroed in on Heuermann as a likely suspect.

The first strong indication was the description of a suspect in the Costello case. Her boyfriend told of having seen a man who looked like Heuermann and described the car he was driving, a first-generation Chevrolet Avalanche.  New York State Police investigator Tifini Atai, through a motor vehicle database check, linked the truck to Heuermann.

While the Gilgo investigation snowballed with evidence, Zacarese started making flow charts and composite videos of the various crime scenes for investigators — a grisly collage of the mostly skeletonized bodies as they were found along Ocean Parkway and other places in Suffolk County.

The paper towel

Although every Gilgo victim had an individual story, investigators treated all of them as part of a larger pattern, Zacarese said.

"This isn’t one murder, this is a story of multiple murders, and that is exactly how we put our gang cases together. … In those cases, we charged 15 to 30 different crimes in one story, and this is the exactly the same way," he said.

After Heuermann was arrested in July 2023, investigators did extensive searches of his home in Massapequa and came up with mountains of evidence. Zacarese and others on the task force were keeping an eye out in their searches for possible trophies Heuermann may have kept from his victims — drivers licenses, jewelry — but found nothing like that.

Megan Waterman's remains provided a crucial clue when investigators found a crumpled piece of Bounty paper towel at the crime scene. Tierney had his staff look for any pieces of paper towel in the Heuermann house that might match the find at the crime scene. In a methodical piece of detective work, investigators had determined that the paper towel found near Waterman — apparently to gag her — had a decorative pattern that the company said was only produced in 2010, the year Waterman disappeared.

While searching Heuermann’s workbench in his basement, investigators found a piece of the exact same paper towel. A shopping receipt found in the search showed the paper towel had been purchased in April 2010, about two months before Waterman went missing.

“We were very excited about that,” Tierney said of the paper towel find. “We have a lot of these small pieces, you weave it all together and create a powerful narrative."

The evidence grew stronger

For Tierney, one of the most telling moments was the information provided by Google about Heuermann’s various explicit sexual searches on the internet. Until then, Tierney said the investigators were looking for any evidence that might poke a hole in their suspicion about Heuermann. But the case against him only grew stronger.

“It just got better, and better and better,” Tierney said. “One piece of evidence came in and it was great and then another piece of evidence came in and it was great. It was just one thing after another.”

Nothing was too small. Single hairs found on the bodies by Clyde Wells, of the Suffolk County crime laboratory, were stored, and when DNA technology progressed they were analyzed and found to be very close genetic comparisons to Heuermann or his family members. Former Suffolk Police Commissioner Geraldine Hart had pushed hard during her time at the helm to pursue advanced DNA techniques to analyze the case.

The aftermath

In the days since Heuermann's guilty plea, a documentary has unveiled chilling new details about how the Long Island serial killer went about choosing his victims and how he told his family he killed them, based on interviews with relatives who spoke to Heuermann in secret meetings leading to the agreement. In one episode, Heuermann told his ex-wife he killed seven of his eight victims inside their Massapequa Park home.

His ex-wfie, Asa Ellerup, also says Heuermann told her the eight women he admitted to killing are his only victims, according to a teaser clip released by Peacock on Monday.

"I said to him, ‘So Mr. Heuermann, I understand that you are confessing to me on those murders. Can you tell me how many of these women did you kill?’ " Ellerup says in the teaser. "He said, ‘Eight.’ "

And in the final installment of Peacock’s "Gilgo Beach Serial Killer: House of Secrets," viewers learn Heuermann had a four-day killing ritual, building trust with his victims before ending their lives in a basement "kill room" and dumping their remains near Gilgo Beach.

By the time Heuermann killed what he says was his eighth and final victim, the practice became so routine his stopwatch informed him it took just 37 seconds to dispose of the remains of Amber Lynn Costello along the north side of Ocean Parkway in September 2010, Sayville therapist Alison Winter discloses in the episode.

"He would hit the timer, dump the body, get back in the truck and hit the timer again," said Winter, who participated in the series after Heuermann and his family waived their rights to patient privacy. "Clearly, he enjoyed killing and it became a sickness for him. It became an outlet. It became an obsession."

Zacarese said that he was convinced that had Heuermann gone to trial he would have been convicted; the evidence was just so overwhelming. But he and the others believe it was best for the families that a trial was avoided.

“It would have been a months- and monthslong trial, and they had been through so much over so many years,” Zacarese said.

Tierney admitted that Gilgo occupied most of every day since he became district attorney, and the conclusion of the case has created a void for him — a feeling that is not uncommon when a big investigation of any kind winds down.

But Tierney, Zacarese and the others who worked on the task force know that any respite is only temporary. There are over 300 cases of unidentified human remains in Suffolk County going back decades. Asked if some of those cases could be linked to Heuermann, Tierney said that the investigation was continuing, thanks to what he calls the “Zacarese model.”

“It gives us the opportunity to take the apparatus that we built and apply it to these other cases,” Tierney said.

Newsday's Grant Parpan contributed to this story.