Subscribe in a ReaderDNA & Crime Labs Make the News (again).
July 21st, 2008 Filed Under Crime Lab, Legal News
Full article by Jason Felch and Maura Dolan can be read in the Los Angeles Times here.
Prosecutors and crime labs across the country routinely use numbers that exaggerate the significance of DNA matches in “cold hit” cases, in which a suspect is identified through a database search.Jurors are often told that the odds of a coincidental match are hundreds of thousands of times more remote than they actually are, according to a review of scientific literature and interviews with leading authorities in the field.Two national scientific committees, including the FBI’s DNA advisory board, have recommended portraying the odds more conservatively. But interviews with expert witnesses and DNA analysts from crime labs across the country show that few if any have adopted that approach.The FBI lab, which oversees the nation’s offender databases, has disregarded the recommendation of its own advisory board, bureau officials acknowledged. So far, the courts have ruled in law enforcement’s favor on this issue.As a result, some experts fear, a technology best known for freeing the innocent could be causing its own miscarriages of justice.”It is only a matter of time until someone is wrongfully convicted because of this,” said Keith Devlin, a Stanford mathematician who has studied the problem.DNA profiles are widely perceived as a unique genetic fingerprint. In fact, they are slivers of the human genome — up to 13 markers that contain about a millionth of the information on all the chromosomes. Relatives often share many markers, and even unrelated people on average share two or three.So DNA “matches” by themselves can never definitively link someone to a crime.The best science can do is to estimate the likelihood that a match has occurred by sheer chance. These statistics are easily distorted or misunderstood by lawyers, judges, juries and even expert witnesses.
Post Linx
Permalink | Trackback |
|
Print This Article |
Comments
Leave a Reply