Suffolk County prosecutors can use high-tech DNA evidence against accused Gilgo Beach serial killer, NYC architect Rex Heuermann

Heuermann, the suspect in the Gilgo Beach serial killings will face just one trial for the murders of seven sex workers, a Long Island judge said in a ruling Tuesday

The decision by Suffolk County Judge Tim Mazzei is a short in the arm for the prosecution case, which hinges on DNA

Heuermann, 61, is accused of killing Valerie Mack, 24, Jessica Taylor, 20, Megan Waterman, 22, Melissa Barthelemy, 24, Maureen Brainard-Barnes, 25, Sandra Costilla, 28, and Amber Lynn Costello, 27

Heuermann has pled not guilty to all seven murder charges and his lawyers fought hard to exclude DNA evidence, the only physical evidence linking him to the killings

Serial murder suspect Rex Heuermann – aka Gilgo Beach serial killer appearing in Judge Tim Mazzei’s courtroom at Suffolk County Court on September 3, 2025, in Riverhead, NY

Alleged serial killer Rex Heuermann, it has been decided will face a single combined trial for the murders of seven sex workers, a Long Island judge said in a bombshell ruling Tuesday.
The decision by Judge Tim Mazzei is a boost for Suffolk County District Attorney Ray Tierney, whose case against the disgraced New York based architect hinges largely on DNA.
“If I wasn’t confident in this case I would’ve never brought it to trial,” Tierney told reporters.

Suffolk County Judge Tim Mazzei Mazzei ruled earlier this month that crucial DNA evidence could be used in the case against the 61-year-old Heuermann who is accused of killing multiple sex workers in the New York metro area between 1993 and 2010

Heuermann’s lawyer, Michael Brown, had challenged the DNA evidence and sought to have his client tried separately for each of the seven sex workers he is accused of killing.
Mazzei ruled earlier this month that crucial DNA evidence could be used in the case against the 61-year-old accused murdering multiple sex workers in the New York metro area.
Leading up to Tuesday’s ruling, Brown had challenged the introduction of the DNA evidence. The DNA matches link Heuermann to seven sex workers found dead along a desolate stretch of Long Island, in New York.
Heuermann is accused of killing Valerie Mack, 24, Jessica Taylor, 20, Megan Waterman, 22, Melissa Barthelemy, 24, Maureen Brainard-Barnes, 25, Sandra Costilla, 28, and Amber Lynn Costello, 27. All were killed during a 17-year killing spree.
Heuermann has pled not guilty to all seven murder charges.

Alleged Heuermann victims: [Top row, L-R], Maureen Brainard-Barnes, Megan Waterman, Melissa Barthelemy, Amber Lynn Costello. [Bottom L-R], Sandra Costilla, Jessica Taylor and Valerie Mack

Suffolk County DA Ray Tierney speaks outside the courtroom where the suspected ‘Gilgo Beach serial killer’ Rex Heuermann appeared at Riverhead Court on Wednesday, Sept. 3, 2025.

This case involves is wrapped in a 30-year investigation. Back in 2011, a dive team [photo], from the Suffolk County Police Dept. searches for possible Gilgo victims

The bodies were dumped between 1993 and 2010, but the murders remain unsolved until former NYPD bigwig Rodney Harrison took over as Suffolk County police commissioner and reopened the case, leading to Heuermann’s arrest in July 2023.
Investigators then carried out two thorough searches of the Heuermann home in Massapequa Park, which led to the alleged discovery of a grisly “planning document” allegedly kept by the accused killer, including a “lessons learned” section.
“I think a big consideration by the court, which was stated in their decision, was that planning document,” Tierney said. “That planning document talks about murders that had occurred, that are about to occur and that are going to occur in the future.”
The architect, who denies responsibility for the murders, has since been held without bail, as investigations are concluded pre-trial.

Full montage of the Gilgo beach victims in a 17-year span. All, with the exception of an infant, were New York metro area sex workers

Brown has called the DNA evidence “magic,” and moved to have it thrown out while asking that each of the murders be the subject of separate trials.
“We’re not making motions for the sake of making motions,” he said outside the courtroom. “We’re making motions because we are confident in the law and confident in our position.
“Ultimately, we do not make the decision,” he said. 
The DNA evidence, processed by Astrea Forensics of California, was tested using high-tech science that allowed damaged samples to be used for the first time in a New York State courtroom.
At the September 3 court hearing, the defense position was that the Lab is not licensed in the state of New York. Using evidence it processed would be a violation the State’s health laws.

The break through in the 30-year long serial killer mystery with bodies dumped along the stretch of Gilgo Beach in Suffolk County, came with the arrest of Rex Heuermann, [photo], a married New York city architect, in 2023

In 2024, prosecutors revealed they had recovered from Heuermann’s computer files what they describe as a “blueprint” for the killings, including a series of checklists with reminders to limit noise, clean the bodies and destroy evidence.
Prosecutors also have a second DNA analysis completed by Mitotyping Technologies, a separate crime lab that used more traditional methods long accepted in New York courts.
Similarly, those set of findings also convincingly link hairs found on some victims to either Heuermann or members of his family.
The prosecution led by DA Ray Tierney, intends to call “well over” 100 witnesses from 15 different states to testify at the upcoming trial, with more than 6.5 million documents entered into evidence.
The repartee by defense calls the 100 terabytes of evidence “a mountain of a mountain.
“You got to remember we’re talking about 30 years of investigation,” Brown said.
“We’re talking about seven victims. So, it is an enormous amount of discovery.”

Over the years, the Long Island serial killer’s victims were found along Ocean Parkway. as mapped by Suffolk County police

Police respond to a scene where a body was discovered near Gilgo Beach on Long Island, in April 2011

We anticipated the judge’s DNA ruling, was the reaction of Bob Macedonio, the lawyer representing Heuermann’s ex-wife, Asa Ellerup.
The high-stakes case has been difficult on Ellerup and her children, Victoria Heuermann and stepson Christopher Sheridan, the family’s lawyer said.
Investigators have said that as he disposed of his victims, Heuermann used items from his house, including tape, belts, bags and a surgical drape, that had traces of hair from his wife and daughter.
While the family moved out of the home they shared with the suspect shortly after his arrest and remained largely incommunicado, still according to their lawyer, “The longer this drags, the longer [the family], have to basically have their lives on hold.
“They cannot move forward until the conclusion of this case,” Macedonio said.