[Infowarrior] - DNA Evidence Can Be Fabricated, Scientists Show

[Richard Forno]

August 18, 2009
DNA Evidence Can Be Fabricated, Scientists Show
By ANDREW POLLACK
http://www.nytimes.com/2009/08/18/science/18dna.html?_r=1&src=twt&twt=nytimes&pagewanted=print
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.”

John M. Butler, leader of the human identity testing project at the  
National Institute of Standards and Technology, said he was “impressed  
at how well they were able to fabricate the fake DNA profiles.”  
However, he added, “I think your average criminal wouldn’t be able to  
do something like that.”

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.

Of course, a drinking cup or piece of hair might itself be left at a  
crime scene to frame someone, but blood or saliva may be more  
believable.

The authors of the paper took blood from a woman and centrifuged it to  
remove the white cells, which contain DNA. To the remaining red cells  
they added DNA that had been amplified from a man’s hair.

Since red cells do not contain DNA, all of the genetic material in the  
blood sample was from the man. The authors sent it to a leading  
American forensics laboratory, which analyzed it as if it were 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 cloned tiny  
DNA snippets representing the common variants at each spot, creating a  
library of such snippets. To prepare a DNA sample matching any  
profile, they just mixed the proper snippets together. They said that  
a library of 425 different DNA snippets would be enough to cover every  
conceivable profile.

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 are attached  
to the DNA at specific points, usually to inactivate genes.