Thursday, October 15, 2026
After nearly six months of hearings, Suffolk County Supreme Court Judge Tim Mazzei ruled in a written decision on Sept. 3 that the DNA evidence connecting alleged Gilgo Beach killer Rex Heuermann to several victims, obtained through a new type of DNA testing, will be admissible in Heuermann’s trial.
“Astrea Forensics’ use of whole genome sequencing to generate SNP data and create a DNA profile,” Mazzei wrote, “is generally accepted as reliable within the scientific community,” based on the testimony of prosecution witnesses Kelley Harris, an associate professor of genome sciences at the University of Washington, and Richard Green, founder of Astrea Labs in California.
Mazzei also wrote in his opinion that “neither of the defendant’s expert witnesses controverted Astrea Forensics’ use of whole genome sequencing, to extract DNA from rootless hairs to generate SNP data and create a DNA profile.”
Suffolk County District Attorney Ray Tierney praised his staff and Mazzei’s decision outside the courtroom at the Arthur M. Cromarty Criminal Court in Riverhead. “The reason why we were able to prevail was one simple reason: The science was on our side,” Tierney said, in front of several family members of victims of the Gilgo murders who chose not to speak.
Prosecutors have said that Astrea Forensics linked Heuermann to six of the seven killings he is alleged to have committed over the course of at least two decades, beginning in 1993, through the testing of rootless hairs found at the crime scenes and comparative analysis of those hairs to DNA samples obtained from Heuermann and family members. His defense team has argued that the technology is new and unproven.
Five witnesses testified in a Frye hearing, a legal proceeding, also known as a general acceptance hearing, used to determine whether scientific evidence presented in court is widely accepted and considered valid within the relevant scientific community.
The admittance of DNA by Mazzei’s ruling could create a statewide precedent. Prior to his decision, Astrea’s technology had only been admitted in court in Idaho.
Heuermann's defense filed another motion based on the court's decision, alleging that the use of Astrea Forensics to analyze Heuermann’s DNA violates New York state health law.
“It criminalizes this very type of action,” Michael Brown, Heuermann’s court-appointed lawyer said, “which is an out-of-state, non-permitted laboratory for profit to test and offer evidence in the state of New York on a criminal case.”
The motion was filed on Sept. 3 with a return date of Sept. 17 — the same date the prosecution will certify its case. The Suffolk County district attorney’s office will answer the motion on Sept. 22.
Heuermann’s defense has been trying to sever the case into separate murder cases, while the prosecution has pushed to have the whole case combined in one trial. Mazzei called all parties back to court on Sept. 23, when he anticipates ruling on both motions.
Heuermann, 61, a Massapequa Park resident, now stands charged with the murders of a total of seven people: Melissa Barthelemy, Maureen Brainard-Barnes, Amber Lynn Costello, Megan Waterman, Jessica Taylor, Sandra Costilla and Valerie Mack.
He has pleaded not guilty to all of the charges, and has maintained his innocence since his July 2023 arrest.
