FORGET everything you learned from CSI: Crime Scene Investigation – DNA evidence can be faked, scientists say, but there is a solution.
Israeli scientists showed that anyone can make fake DNA with some basic equipment and know-how.
It can then be incorporated into genuine human blood or saliva, or directly planted at a crime scene.
“Current forensic procedure fails to distinguish between such samples of blood, saliva and touched surfaces with artificial DNA,” the scientists wrote in Forensic Science International: Genetics.
“You can take a used cup of coffee or a cigarette butt, send it to a laboratory, and for a relatively small sum of money have their DNA identified, produced and sent back to you in a test tube,” said Elon Ganor, co-founder of Israeli DNA analysis company Nucleix.
The DNA samples, which are produced using a standard technique called whole genome amplification, could then be planted at a crime scene.
Forensic DNA profiling is today one of the most powerful tools applied on crime scenes, and is often used to convict or acquit suspects in rape and murder cases.
Researchers at Nucleix demonstrated how artificial DNA could be implanted into real blood by using a centrifuge to separate red and white blood cells and then placing the DNA in the former, giving the blood a new profile.
As part of the experiment, a modified blood sample was sent to a US laboratory that works with FBI forensic teams.
It failed to catch the forgery, Mr Ganor said.
The real deal
To combat the practice, Nucleix has developed a DNA authentication method that distinguishes between real and fake samples.
“We have come up with a solution that should become an integral part of the standard DNA tests today and seal the hole that has been opened in what has become the gold-standard in forensics,” Mr Ganor said.
The new process was tested on natural and artificial samples of blood, saliva and touched surfaces, with complete success, Nucleix said.
It also identifies “contaminated” DNA that has been mixed with two or more samples.
Although most of the DNA sequence is identical in all humans, forensic scientists scan 18 regions on the sequence that vary from person to person, allowing the identification of a single person with extremely high accuracy.
“DNA is in many cases what breaks trial suspects and allows their conviction ‘beyond reasonable doubt,”‘ said DNA analysis expert Adam Friedmann at Israel’s Ruppin Academic Centre.
“DNA profiling is an excellent technique that is improving by leaps and bounds,” he said.
“There is nearly a 100 per cent accuracy in identification,” he said, adding that there is less and less need to bring other evidence linking a person to a crime scene.
“Courts in Israel, the United States and elsewhere are relying more and more on DNA forensic evidence to close cases,” Mr Friedmann said. AFP