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Forensic DNA Testing Concerns

New York's chief medical examiner office has pioneered ways to analyze small, or even mixed, samples of genetic material found at crime scenes. However, in an investigative piece, the New York Times and ProPublica report that the office's approaches are being questioned.

ProPublica's Lauren Kirchner writes that issues have been raised with both the amount of starting material the approaches work with and the statistical analyses of the results. For instance, she notes that the investigation of an attack in Brooklyn relied on a mixed sample of 97.9 picograms of DNA to link Mayer Herskovic to the scene. Additionally, she reports that the lab's high-sensitivity approach that relies on extra rounds of amplification, which the lab had said it would only use in instance where there was more than 20 picograms of genetic material to work with, has been used in cases where less was available.

At the same time, there are concerns about its tool that calculates the odds that someone's DNA is in a given sample, according to Kirchner. In many cases, she says defense experts weren't allowed access to the code, but notes that once they were given it, they found that it discounted some data.

The medical examiner office recently retired these approaches in favor of newer, more widely used ones, the piece adds, noting that the office stands by its former techniques.