DNA is often wrong in criminal cases

Boise State University Professor Dr. Greg Hampikian is a Biologist whose work has identified persons wrongly accused and convicted of crimes. He is regarded as one of the foremost forensic DNA experts in the United States and beyond. He is the founder of the Idaho Innocence Project, which has helped exact hundreds of persons wrongly convicted along with other state Innocence Projects. Those convictions have often been based on faulty science and false confessions. So when he tells us that DNA testing at crime labs is suspect and results may be misleading, we should pay attention.

Dr. Hampikian’s op-ed in the New York Times yesterday should sound a bell for any person who faces criminal charges supported by DNA test results. Dr. Hampikian reports that in a recent reliability study, 74 out of 108 crime laboratories implicated an innocent person in a hypothetical bank robbery.

Dr. Hampikian cites a study by the National Institute of Standards and Testing. Here’s what he says happened:

“Researchers from the National Institute of Standards and Technology gave the same DNA mixture to about 105 American crime laboratories and three Canadian labs and asked them to compare it with DNA from three suspects from a mock bank robbery.

The first two suspects’ DNA was part of the mixture, and most labs correctly matched their DNA to the evidence. However, 74 labs wrongly said the sample included DNA evidence from the third suspect, an ‘innocent person’ who should have been cleared of the hypothetical felony.”

Dr. Hampikian also reports on the interpretation of DNA mixtures from three or more persons. The statistics generated by laboratories relied upon to explain the likelihood of an innocent match. He reports that laboratories “analyzing the same evidence calculated vastly different statistics. Among 108 crime labs in the study, the match statistics varied over 100 trillion-fold.”

Those statistics are critical in defense of a person whose freedom depends on explaining an apparent DNA match. Prosecutors typically rely on Ph.D. scientists to explain the likelihood of the significance of finding the defendant’s DNA at the scene of a crime. Those witnesses inevitably offer their expert opinion that the chances of a sample found at the scene of the crime (blood, for example) having come from someone other than the defendant is a virtual statistical impossibility. Consider some crazy number – like the chance that blood came from someone other than the defendant is on the order of 1 in 100 million. That enormous statistical improbability almost certainly seals the defendant’s conviction, unless there is another explanation. If the statistics generated by different labs vary by over 100 trillion-fold, the statistical evidence’s value may be suspect.

The authors of the study did not immediately publish their work in peer-reviewed journals or sound an alarm that shoddy lab work poses a considerable risk for criminal defendants. They apparently kept quiet, and when they finally did publish the results, they seemingly tried to tinker with its use by the lawyers who face such evidence in court.

So if the science is accurate, and by now we know it is, but the laboratories are not handling the evidence to get reliable results, people will be wrongly convicted. Hampikian points to just such a case in Nevada, where Dwayne Jackson faced a home invasion and kidnapping charge when he was 18 years old. The state’s evidence included a DNA match tying him to the scene. Told he would spend life in prison if he went to trial. He pleads guilty to reduced charges in 2003, only to later be freed because the crime laboratory had accidentally switched his sample with another suspect’s tube. He spent nearly four years in prison before the lab admitted they got it wrong.

Dr. Hampikian points to computer programs that can assist in excluding innocent profiles, thereby providing a means of correcting past errors and preventing errors in the future. His work reviewing cases using such software has already identified innocent persons wrongly convicted in New Mexico, Indiana, Montana, and a new suspect in a 23-year-old murder.

If you are a lawyer facing DNA evidence, get some help. Your client may not be guilty, even if some lab says otherwise. Be prepared and fight on.

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