Andrew Pollack, in a New York Times article dated August 17, 2009, reported that scientists in Israel have demonstrated that it is possible to fabricate DNA evidence, undermining the credibility of the latest gold standard of proof in criminal cases.
He cited “Science News,” writer Dan Frumkin, a founder of Nucleix, a company based in Tel Aviv that has developed a test to distinguish real DNA samples from fake ones.
Dr. Frumkin published his findings at the online journal, Forensic Science International: Genetics. He stated that any biology undergraduate could engineer a crime scene. His study showed that if someone had access to a DNA profile in a database, he could construct a blood or saliva sample for that person to match their profile without obtaining any tissue from him/her. Tania Simoncelli, science adviser to the American Civil Liberties Union, said that DNA is easier to plant at a crime scene than fingerprints.
The scientists fabricated DNA samples two ways. One required a real, if tiny, DNA sample, perhaps from a strand of hair or drinking cup. They amplified the tiny sample into a large quantity of DNA using a standard technique called whole genome amplification.
This method involves taking blood from one person, centrifuging it to remove the white cells, which contain the DNA, and adding to the remaining red cells DNA that has been amplified from another person’s hair or spit.
In the demonstration case the original blood was from a female. Since red cells do not contain DNA, all of the genetic material in the blood sample was from the hair sample of the other person, a man. It was sent to a leading American forensics laboratory, which determined it to be a normal sample of a man’s blood.
The other technique relied on DNA profiles stored in law enforcement databases as a series of numbers and letters corresponding to variations at 13 spots in a person’s genome.
From a pooled sample of many people’s DNA, the scientists can clone tiny DNA snippets representing the common variants, creating a library of such snippets. To prepare a DNA sample matching any profile, they just mix the proper snippets together. A library of 425 different DNA snippets would be enough to cover every conceivable profile.
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.
It may be possible to scavenge someone’s DNA from a discarded drinking cup or cigarette butt and turn it into a saliva sample and submit it to a genetic testing company to determine ancestry or the risk of getting various diseases, reported Gail H. Javitt of the Genetics and Public Policy Center at Johns Hopkins University.
Nucleix’s test to tell if a sample has been fabricated relies on the fact that amplified DNA — which would be used in either deception — is not methylated, meaning it lacks certain molecules that tend to be attached to the DNA at specific points.