FBI Fights Testing For False DNA Matches

Statesman writes "The Los Angeles Times reports that an Arizona crime lab technician found two felons with remarkably similar genetic profiles, so similar that they would ordinarily be accepted in court as a match, but one felon was black and the other white. The FBI estimated the odds of unrelated people sharing those genetic markers to be as remote as 1 in 113 billion. Dozens of similar matches have been found, and these findings raise questions about the accuracy of the FBI's DNA statistics. Scientists and legal experts want to test the accuracy of official statistics using the nearly 6 million profiles in CODIS, the national system that includes most state and local databases. The FBI has tried to block distribution of the Arizona results and is blocking people from performing similar searches using CODIS. A legal fight is brewing over whether the nation's genetic databases ought to be opened to wider scrutiny. At stake is the credibility of the odds often cited in DNA cases, which can suggest an all but certain link between a suspect and a crime scene."

Comments

Re:We're seeing no such thing.

[Mistlefoot]

This is also shown in the "birthday paradox". If you have 23 random people in a room, the odds are 50/50 that a birthday will be shared.

http://en.wikipedia.org/wiki/Birthday_paradox

Re:An example of the birthday problem

[jd]

That would be fair enough, except for this: The FBI has tried to block distribution of the Arizona results and is blocking people from performing similar searches using CODIS. If this is correct, then the FBI does not have confidence in its own claims, which is worrisome. If they had confidence, they would have no need to block distribution of anything, indeed they would increase confidence in the system by having others validate that the probability of a false match is staggeringly low. I do not trust those who will not trust their own integrity.