Gilgo Beach killings: Lawyer for alleged serial killer Rex Heuermann zeroes in on lab's software to attack credibility of DNA evidence 

The defense for alleged Gilgo Beach serial killer Rex A. Heuermann attempted Thursday to discredit the nuclear DNA methods a California laboratory used to link him to the killings, questioning the veracity by which the lab's software has been scrutinized and the impact the technology has had in the world of forensics.

Lead defense attorney Michael J. Brown, noting a mathematical error in the formula published in papers supporting the software used by Astrea Forensics, asked the founder of the lab how his software can be widely accepted in the scientific community if the published formula is incorrect.

"There's a typo in the paper," Astrea co-founder Richard Green acknowledged, downplaying the significance of the mistake, which was repeated in patent filings related to the software, IBDGem.

"The math is correct in the code [of the software]," Green would later clarify for the prosecution.

Thursday's testimony marked the sixth day of an admissibility hearing tasking prosecutors with proving the whole genome sequencing methods used by the lab are widely accepted by the relevant scientific community, therefore meeting the Frye standard of scientific evidence used in New York.

Acting State Supreme Court Justice Timothy Mazzei will make that determination at the conclusion of the hearing, deciding if the DNA evidence will be admissible at trial.

Heuermann, 61, of Massapequa Park, was arrested in July 2023 and has pleaded not guilty to the killings of seven women from 1993 to 2010.

Prosecutors have said Astrea Forensics linked him to six of the seven killings through the testing of rootless hair found at the crime scenes and comparative analysis of those hairs to DNA samples obtained by Heuermann and family members.

Green testified this week that Astrea’s process includes extracting DNA from degraded hair samples, sequencing the DNA and then comparing it to a sample of a known subject to establish the likelihood of the source.

Over more than four hours of cross-examination Wednesday and Thursday, Brown pressed Green on the lack of times his IBDGem software has been used in criminal proceedings or scrutinized by other scientists through peer review and citations.

Brown noted Green's earlier testimony that DNA evidence using his technology has been used in only one criminal trial — in Idaho. The defense attorney also pointed out that Green's paper on IBDGem has been cited just eight times by other scientists in the past two years, comparing it with the more than 1,000 times that a paper he co-authored on Neanderthals has been cited.

"That's an outlier," Green shot back. "Very few papers get cited thousands of times."

Brown also questioned why no accredited crime labs are using the IBDGem software and the effectiveness of a technology that uses a database of just 2,500 individuals as a reference panel to offer comparisons to the suspect DNA.

Brown likened the use of the reference panel, known as the 1000 Genomes Project, to using a small phone book to find a specific name when larger books are available.

"That's a terrible analogy," Green told Assistant District Attorney Nicholas Santomartino on redirect. "It's just not what we're doing at all."

Green was the third prosecution witness called in the hearing. Prosecutors have until next week to determine if they will call more witnesses.

The hearing will then continue at a later date with the defense calling two witnesses of their own, Brown said.

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.