Gilgo Beach killings: Investigators to announce 'significant development' in the case of Rex Heuermann

Investigators are expected to announce a "significant development" in the case of alleged Gilgo Beach serial killer Rex A. Heuermann when he returns to court Tuesday morning, the Suffolk County District Attorney’s Office said.

Reached by telephone Monday, Suffolk District Attorney Ray Tierney declined to discuss the specifics of the announcement. Defense attorney Michael Brown, of Central Islip, told Newsday he has not been briefed on any new developments.

The district attorney's office said it has scheduled a news briefing following Heuermann's 9:30 a.m. appearance before State Supreme Court Justice Timothy Mazzei in Suffolk County Court in Riverhead.

The district attorney has previously stated Heuermann, already charged in six killings, remains a suspect in the other decades-old unsolved killings along Ocean Parkway near Gilgo Beach, including Valerie Mack, of New Jersey, whose parents told Newsday they plan to attend Tuesday’s news  conference. Her half-sister, Tricia Hazen, said she intends to watch the news conference from home.

Tierney in June named Heuermann as a suspect in Mack’s 2000 killing, when prosecutors unveiled a document they discovered on a device seized from Heuermann’s home that referenced the Mill Road location where Mack’s remains were first discovered by hunters as a potential "dump site."

"If we’re able to develop more information and get to the point where we can charge him, we’ll talk about it," Tierney said of the Mack investigation at a June 6 news conference.

Ed Mack, the father of Valerie Mack, said in June he believed prosecutors would likely charge Heuermann in her death before the end of the year. He said at the time he was pleased with how the case had progressed.

"It looks like they are really mining the evidence," Edwin Mack said then.

Mack told Newsday last week that police have been visiting family in New Jersey tracking his daughter’s movements in the days before she disappeared in October 2000.

A hunting dog led the hunters to Mack’s body, which was located about 200 feet off Halsey Manor Road near a utility right of way on Nov. 19, 2000, Newsday reported at the time. Her body had been severed into pieces and placed into several large dark-colored garbage bags.

Additional body parts were discovered more than a decade later near Gilgo Beach, investigators have said. Until she was identified in February 2020, Mack was referred to as Jane Doe No. 6.

Tierney has also declined to rule out Heuermann as a suspect in the death of Long Island native Karen Vergata, whose remains were found farther west along Ocean Parkway in 2011 and on Fire Island in 1996. Three additional sets of human remains connected to the Gilgo Beach investigation remain unidentified.

Heuermann, 61, an architectural consultant, was arrested near his Manhattan office on July 13, 2023. He was arraigned the following morning on charges of first- and second-degree murder in the killings of Megan Waterman, Melissa Barthelemy and Amber Lynn Costello, who were each killed within a year of each other in 2009 and 2010. Heuermann was then arraigned on a superseding indictment in January charging him with second-degree murder in the death of Maureen-Brainard Barnes, who was killed in 2007. Waterman, Barthelemy, Costello and Brainard-Barnes, referred to by investigators as the Gilgo Four, were the first sets of remains discovered near Gilgo Beach in 2010.

A second superseding indictment in June charged Heuermann with second-degree murder in the 2003 killing of New York City resident Jessica Taylor, whose remains were also found in Manorville and near Gilgo Beach, and Sandra Costilla, of Queens, whose body was discovered in the Southampton hamlet of North Sea in 1993.

Each of the six alleged victims, and Mack and Vergata, engaged in sex work, police and prosecutors have said.

Prosecutors have said DNA evidence links Heuermann to the six charged victims.

Witness statements and cellphone data also ties Heuermann to some of the women, several of whom had ties to the New York City area where he worked. Prosecutors have also said financial records and witness statements show each of the women were killed at times Heuermann, a married father of two, was alone in his home.

Tierney has alleged Heuermann took notes from books about serial killings and that evidence found in his home showed he had an interest in torture.

Heuermann, who has been held in isolation at the Suffolk County Jail in Riverhead since his arrest, has denied the charges against him and his defense team has said it intends to challenge the DNA methods used by investigators.

Mazzei said at Heuermann’s appearance in October that he intends to schedule hearings related to the DNA evidence in the case at Tuesday’s court appearance. The judge said an initial trial date might also be set.

With Anthony M. DeStefano

By Grant Parpan

grant.parpan@newsday.com@GrantParpan

Grant Parpan covers Suffolk County courts and federal courts for Newsday. A Long Island native, he joined Newsday in 2022.