Saturday, July 27, 2013

Contamination or Sasquatch in Forensic Laboratories -- Which Is it?

DNA Diagnostics, Inc., is “a laboratory that provides multi-species testing including human as well as animal DNA testing for individuals, law enforcement, breed associations, and state regulatory agencies.”The lab
  • “participates in both human and animal proficiency testing”
  • has staff who are “eminently qualified to provide superior DNA testing services” and of “unquestionable quality,” and
  • performs “testing ... of the highest quality” (including “high volume genetic testing”) with “state of the art instrumentation and modern facilities .. on the cutting edge of technology in DNA testing.
Thus, “[s]taff members ... have been accepted in court as experts in human and animal forensic DNA testing ... for the prosecution and the defense and in [state and federal] criminal and civil cases.”

These attributes are what one would want in a forensic laboratory, and the work of this laboratory is nothing short of amazing. Last November, it issued a press release that “calls on public officials and law enforcement to immediately recognize the Sasquatch as an indigenous people.”

The Sasquatch? As in Bigfoot?

Absolutely. A “team of experts in genetics, forensics, imaging and pathology, led by Dr. Melba S. Ketchum ... sequenced 3 complete Sasquatch nuclear genomes and determined the species is a human hybrid” living in North America. The team discovered that “the legendary Sasquatch is a human relative that arose approximately 15,000 years ago as a hybrid cross of modern Homo sapiens with an unknown primate species.” Mitochondrial and “next generation sequencing [of] 3 whole nuclear genomes ... indicate that the North American Sasquatch is a hybrid species, the result of males of an unknown hominin species crossing with female Homo sapiens.”

This might seem amusing, but the study director’s responses to other scientists who interpret the results, not as proof of a hybrid species, but as an indication of contaminated samples, sound eerily like what one hears in court. John Timmer, a science writer and molecular biologist, describes what he found when he examined the “genomes” and conferred with her:
In cases where the hair comes attached to its follicle, it's possible to extract DNA from its cells. And that is exactly what the bigfoot team did, using a standard forensic procedure that was meant to remove any other DNA that the hair had picked up in the interim. If everything worked as expected, the only DNA present should be from whatever organism the fur originated from.

And, in Ketchum's view, that's exactly what happened. They worked according to procedure, isolating DNA from the hair follicles and taking precautions to rule out contamination by DNA from anyone that was involved in the work. Because of this, Ketchum is confident that any DNA that came from the samples once belonged to whatever creature deposited the fur in the woods—no matter how confusing the results it produced were. "The mito [mitochondrial DNA results] should have done it," she argued. "It's non-human hair—it's clearly non-human hair—it was washed and prepared forensically, and it gave a human mitochondrial DNA result. That just doesn't happen."

Ketchum was completely adamant that contamination wasn't a possibility. "We had two different forensics labs extract these samples, and they all turned out non-contaminated, because forensics scientists are experts in contamination. We see it regularly, we know how to deal with mixtures, whether it's a mixture or a contaminated sample, and we certainly know how to find it. And these samples were clean."
Timmer’s article on how science went wrong is well worth reading — and chilling if you think about how DNA Diagnostics’ director -- an eminently qualified expert witness -- might testify about contamination in a more mundane case.


Acknowledgment: Thanks to Joe Cecil for calling John Timmer's article to my attention.

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