Scientists: DNA evidence can be fabricated

From the New York Times:

Scientists in Israel have demonstrated that it is possible to fabricate DNA evidence, undermining the credibility of what has been considered the gold standard of proof in criminal cases.

The scientists fabricated blood and saliva samples containing DNA from a person other than the donor of the blood and saliva. They also showed that if they had access to a DNA profile in a database, they could construct a sample of DNA to match that profile without obtaining any tissue from that person.

“You can just engineer a crime scene,” said Dan Frumkin, lead author of the paper, which has been published online by the journal Forensic Science International: Genetics. “Any biology undergraduate could perform this.”

Dr. Frumkin is a founder of Nucleix, a company based in Tel Aviv that has developed a test to distinguish real DNA samples from fake ones that it hopes to sell to forensics laboratories.

The planting of fabricated DNA evidence at a crime scene is only one implication of the findings. A potential invasion of personal privacy is another.

Using some of the same techniques, it may be possible to scavenge anyone’s DNA from a discarded drinking cup or cigarette butt and turn it into a saliva sample that could be submitted to a genetic testing company that measures ancestry or the risk of getting various diseases. Celebrities might have to fear “genetic paparazzi,” said Gail H. Javitt of the Genetics and Public Policy Center at Johns Hopkins University.

Tania Simoncelli, science adviser to the American Civil Liberties Union, said the findings were worrisome.

“DNA is a lot easier to plant at a crime scene than fingerprints,” she said. “We’re creating a criminal justice system that is increasingly relying on this technology.” ...

Read the rest here. These techniques (for now) likely remain beyond the ability of the average criminal. But think of the possibilities, e.g., for governments and state-funded entities to fabricate evidence against those whom the state deems "undesirable", and who they wish to frame for a crime. Food for thought.

How reliable is DNA?

Article in the L.A. Times on the reliability of DNA evidence. The article discusses several cases where the results of actual matches in a search of DNA databases were more numerous than the expected probabilities would have predicted.

State crime lab analyst Kathryn Troyer was running tests on Arizona's DNA database when she stumbled across two felons with remarkably similar genetic profiles.

The men matched at nine of the 13 locations on chromosomes, or loci, commonly used to distinguish people.

(Click to enlarge. Graphic: L.A. Times)

The FBI estimated the odds of unrelated people sharing those genetic markers to be as remote as 1 in 113 billion. But the mug shots of the two felons suggested that they were not related: One was black, the other white.

In the years after her 2001 discovery, Troyer found dozens of similar matches -- each seeming to defy impossible odds.

As word spread, these findings by a little-known lab worker raised questions about the accuracy of the FBI's DNA statistics and ignited a legal fight over whether the nation's genetic databases ought to be opened to wider scrutiny.

The FBI laboratory, which administers the national DNA database system, tried to stop distribution of Troyer's results and began an aggressive behind-the-scenes campaign to block similar searches elsewhere, even those ordered by courts, a Times investigation found.

At stake is the credibility of the compelling odds often cited in DNA cases, which can suggest an all but certain link between a suspect and a crime scene.
...

Interesting reading. Part of the problem may lie in the way the FBI calculated the initial estimates of genetic marker rarity. The article states that those estimates were derived from samples of a few hundred people of varying ethnic and racial groups. Thus, if the selected sample from which the marker rarity estimates were derived does not in fact reflect that of the larger population, then you'll have potentially large errors in your overall match probability estimates.