Scientist have developed a new, better way of lifting fingerprints on bullets and fragments of explosives even if a criminal has tried cleaning/wiping the evidence. This new technique has been discovered by John Bond, a British physics, whose method British and US authorities have already used to re-open three cold cases.
Fingerprints are a crucial evidence and the conventional method of taking fingerprints has been around for more than 100 years and involves creating a chemical reaction with the sweat left behind on an object to produce an image police can use. However, if a criminal wipes away the surface and thus clean the sweat, there is little left to react with the chemical and regular methods are useless, Bond said in a telephone interview.
This new technique, however, allows the police to produce a fingerprint even if there is no sweat impression to work with. So how exactly does this new technique work? Forensic scientist John Bond of the Northamptonshire Police, in the United Kingdom, developed the technique after discovering that certain metals, including copper and brass, corrode very slightly when touched, leaving behind a faint but indelible fingerprint. This is due to the ionic salt present in fingerprint residue that corrodes the metal surface producing an image that can only be removed by abrasive cleaning of the metal.
Scientists cover the metal with a fine powder and apply a strong electrical charge that makes the dust stick to the corroded areas, producing a potential fingerprint, Bond said. “That very fine powder only sticks to the metal where it is corroded, which means it is only sticking where the fingerprint is and means you see the image of the fingerprint,” said Bond, whose team has published its findings in the Journal of Forensic Sciences and the Journal of Applied Physics. The technique is not foolproof and some people do not secrete enough salt in their sweat to corrode the metal to the point police can get a print, he added.
“The advantage of the new technique is its permanence,” says Ron Singer, crime-laboratory director for the Tarrant County Medical Examiner Crime Lab, in Fort Worth, TX. “It is looking for the minute amount of etching that takes place in the metal–the physical change that has occurred to the surface.” Singer says that the technique could prove more resilient than conventional methods. “If you don’t get it right the first time, you can do it again,” he adds. “One of the major issues in fingerprint analysis is how much of the print is necessary before you can reliably say it is someone’s fingerprint,” says Singer.
I believe that this is a fantastic discovery with a very bright future, that will definitely make solving cases much easier. At least until criminals come up with the way to hide those prints. Although, as far as forensic science is one step ahead, things are under control.
-article by Michael Kahn, rewritten and adapted by administrator-