The DNA software that linked Rex Heuermann to the Gilgo Beach murders was so glitchy that it was updated multiple times after it tied the accused serial killer to the grisly murders, a defense expert testified Tuesday.
Nathaniel Adams, a biotechnology expert for Heuermann’s defense team, testified at a fiery court hearing that the IDBGEM program was prone to misreading genotype data that was used to link the suspected killer to six of the seven sex workers butchered and dumped on Long Island over more than 30 years.
“It’s unreliable,” Adams, a 27-year-old graduate student and systems engineer for Forensic Bioinformantics in Ohio, testified in Suffolk County court. “The software has been updated multiple times since the DNA in this case has been tested.”
He said the software bugs would require a “risk and hazard analysis” to avoid a “catastrophic failure” that could lead to “a miscarriage of justice.”
Adams revealed there here have been 65 small updates, and that even newer software versions of the program have dropped since June 2020, when they tested Heuermann and his family’s DNA.
But Suffolk County District Attorney Ray Tierney scoffed at Adams’ qualifications as an expert on DNA — maintaining his testimony in about 30 other court cases have often been deemed “inadmissible.”
“You’ve been in school for 10 years and have only obtained a bachelor’s degree in all this time?” Tierney said as he grilled Adams on the stand. “You’re supposed to be an expert, but you don’t even know who your adviser was or if you graduated summa cum laude or not.”
DNA is crucial to the prosecution’s case as the most direct link to Heuermann and the killings.
Suffolk prosecutors said they have linked Heuermann, a 61-year-old Manhattan architect from Massapequa Park, through hairs found on the seven victims. They were all sex workers who disappeared between 1993 and 2010 and were later found along desolate stretches of Long Island.
The deaths of the victims — Valerie Mack, 24, Taylor, 20, Megan Waterman, 22, Melissa Barthelemy, 24, Maureen Brainard-Barnes, 25, Sandra Costilla, 28, and Amber Lynn Costello, 27 — remained unsolved until authorities reopened the cold case in 2022.
Heuermann, a married father of two, was arrested in July 2023 for three of the murders and was later tied to the other four through the DNA matches.
Investigators matched some of the victims through DNA links to Heuermann’s wife, Asa Ellerup, and his adult daughter, Victoria Heuermann, authorities said.
Authorities have twice executed search warrants at the Heuermann home, combing through the property, digging up the back yard and testing a basement gun bunker prosecutors believed was a “kill room” — but have not revealed finding any physical evidence.
The DA did uncover a sick computer file, described as a “how to” record on some of the killings and notes that appear to provide tips on how to improve the slayings.
The high-profile serial murder case has captured the nation’s imagination, and is the subject of a newly released three-part Peacock docu-series that features first-ever interviews with Heuermann’s family.
