Whole Genome Sequencing Evidence Allowed In Gilgo Beach Serial Killer Case, A First For New York Courts

The New York trial of an alleged serial killer could open up a whole new avenue for the use of genetic data in court, after a judge allowed the use of whole genome sequencing as evidence – a first for the state.

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The trial in question revolves around a series of at least 11 murders that took place in Long Island between 1993 and 2011, often referred to as the Gilgo Beach killings due to the remains of four victims being found in the coastal location.

Accused of the murders is Rex Heuermann, a Nassau County architect who was arrested and charged with a number of the killings in 2023 and 2024. That move came after hairs were recovered from the victims’ burial sites, with analysis of the DNA contained within them leading investigators to Heuermann.

The precedent for using DNA in criminal cases was first set back in the late 1980s, when the then-new technology of DNA profiling – which compares highly variable regions of DNA unique to an individual – was allowed as evidence in a UK court to help convict double-killer Colin Pitchfork.

Genetics has come a long way since then, and science now has the capability to lay out and analyze the entirety of someone’s DNA down to the individual letter, each A, C, T, and G, even with only a small, old, or degraded sample. This is whole genome sequencing, and it’s what prosecutors used to identify Heuermann as a suspect, comparing single-letter differences in the DNA found at the scene with DNA data submitted to a genealogy service by his family.

However, it hasn’t been used in a New York court before – and Heuermann’s defense attorneys argued that it shouldn’t be, contending that the technique used to analyze the sequence data wasn’t scientifically valid, and the evidence insufficient to link their client to the crimes.

The prosecution, unsurprisingly, disagreed. The solution? A Frye hearing. This is a type of legal proceeding that’s used to determine if scientific evidence that’s intended to be presented in court is widely accepted within the scientific community as valid, known as the Frye standard.

On September 3, Judge Timothy Mazzei ruled that the whole genome sequence evidence could indeed be used. There was another attempt by the defense to get it thrown out, but that request was again rejected on September 23.

The decision is a big deal, not just because it marks the first time this kind of evidence has been used in a New York court, but because of the precedent it could set across the country. Where whole genome sequencing has been used elsewhere in the US before – including California and Idaho – it hasn’t required a Frye hearing. 

The bar that must be reached to meet this standard means that this ruling solidifies the use of whole genome sequencing as valid evidence in criminal cases, and that could provide prosecutors with a lot more confidence in using it, potentially leading to a whole wave of fresh cases.

“This is a big step forward for the use of DNA evidence, because it will allow comparisons and matches with evidence that was previously considered too minuscule, too old or too badly degraded to be considered useful,” Nathan Lents, a biologist at the John Jay College of Criminal Justice in New York City, told Nature. 

“You can bet that cold-case units all over the country are going back through their evidence lockers to see if there are samples that can now be tested with a reasonable chance of success.”