Sunday, April 19, 2009
I Can't Put My Finger On It: Will England's New Fingerprinting Technique Have The Same Fate As Low Copy Number DNA?
Will a new fingerprinting technique from England become the key to solving cold cases in the United States? Or, like low copy number DNA and ear print evidence, will it be something that we decide is as unwanted on these shores as the British monarchy?
According to a recent CNN story,
a groundbreaking technique developed across the Atlantic Ocean in Britain may help Texas police and others to crack cold cases....The technique enables scientists to detect fingerprints on spent bullets and shell casings, even when the print had been wiped off. It works by detecting the minute corrosion of metal caused by sweat, which corrodes the metal in the shape of the fingerprint.
"That sweat is in the pattern of the original fingerprint that was deposited," said John Bond, a forensic scientist for England's Northamptonshire Police and a researcher at the University of Leicester, who developed the technique.
The corrosion is often impossible to see with the naked eye because it's so small -- as small as a micron, which is a millionth of a meter, Bond said.
His method involves dusting the metal with a fine black powder that adheres to the corroded areas, allowing scientists to see the fingerprint.
According to Bond, he has been in contact with American law enforcement officials regarding his technique, and
"All of the inquiries we've had from the U.S. police forces have all been initiated by them," he told CNN. "We never say no, so anybody who says, 'I've got some shell casings, we have some over 30 years old' -- we always say send them and we'll have a look."
All of this sounds promising, but I can't help but think that the technique might have the same problems as low copy number DNA. As I noted in a previous post,
Low copy number DNA allows the genetic profiles of suspects, victims or witnesses to be "uncovered" even when there is only a tiny amount of biological material present, sometimes as small as a milionth of the size of a grain of salt. The technique amplifies these tiny DNA fragments when it is believed that a suspect may have transferred DNA through touch, like the residue believed to have come from cells such as skin or sweat left in a fingerprint. Since this technique was launched in 1999, it has been consistently doubted in the scientific community, and it has thus only been used in the U.K., the Netherlands, and New Zealand.