The bloom is off forensic DNA’s infallibility – Scientific American

Eric Frimpong and Santa Barbara defense attorney Robert Sanger in 2008.

With the FBI making a step to reel in its history of wayward forensic conclusions, Scientific American wades into the “restructuring” of DNA opinions in much the same way. The Fibbies had ample time and warning to rethink and retool their poorly validated use of human hair morphology when DNA profiling began to contradict hair IDs in earnest during the 1990’s. Better late than never, I guess.

Now, in a stroke of irony, DNA is being seen in the media and some scientific forensic circles as subject to similar human foibles. Starting with unintentional transfer of a suspect’s DNA to some other crime scene to much worse.

Its all about the DNA from “touch.” The Santa Barbara’s District Attorneys Office put UCSB soccer star Eric Frimpong into prison (and after release deportation back to Ghana) in 2008 from a touch contact between a female student and his genitals. She was covered in seminal fluids from her unindicted “boyfriend.”  2 bitemark dentists showed up to finish the deal against him. These are same two DA bitemark experts in Bill Richards case from 1997 who recanted their testimony from that case in 2009.

As you will read below, “touch” research is just starting after 20 years of DNA courtroom opinions in the US. In another irony, the testing of DNA “walking” into a crime scene and by direct inference, a sexual assault case, is reported from a forensic science graduate student. Odd? Not really as this is forensics.

When DNA Implicates the Innocent

The criminal justice system’s reliance on DNA evidence, often treated as infallible, carries significant risks.

Until recently, this type of DNA has been regarded as incontrovertible proof of direct contact. But a growing number of studies show that DNA does not always stay put. For example, a person who merely carried a cloth that had been wiped across someone else’s neck could then transfer that person’s DNA onto an object he or she never touched, according to a study published earlier this year in the International Journal of Legal Medicine. Similarly, Cynthia M. Cale, a master’s candidate in human biology at the University of Indianapolis, recently reported in the Journal of Forensic Sciences that a person who uses a steak knife after shaking hands with another person transfers that person’s DNA onto the handle. In fact, in a fifth of the samples she collected, the person identified as the main contributor of DNA never touched the knife. Cale and her colleagues are among several groups now working to establish how easily and how quickly cells can be transferred—and how long they persist. “What we get is what we get,” Cale says, “but it’s how that profile is used and presented that we need to be cautious about.”

Full article from Scientific American.


About csidds

Dr. Michael Bowers is a long time forensic consultant in the US and international court systems.
This entry was posted in AAFS, criminal justice, DNA profiling, Forensic Science and tagged , , , , , . Bookmark the permalink.

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