March 16, 2007 -- CSI's Will Find More Fingerprints With New Technique
Criminals often leave fingerprints than law enforcement agents can’t get. But a new technique, outlined in the journal Chemical Communications, may make many more fingerprints available for recovery and analysis.
Currently, forensic investigators find fingerprints by coating a surface with a watery suspension of gold nanoparticles and citrate ions. In that acidy environment, the gold particles stick to positively charged particles in the fingerprint. A silver ion solution is then used to react with the chemical species left on the print. The final result is an outline of silver along the fingerprint’s ridges.
But the problem with this technique is that the gold solution isn’t stable and results are difficult to repeat, which can be a big problem in a trial. Researchers at the Hebrew University in Jerusalem have stabilized the gold solution by attaching hydrocarbon chains to the gold particles and suspending them in petroleum ether. The result is like putting a rowdy dog on a leash—the gold particles behave. A forensics expert for the US Secret Service said the new fingerprint method would greatly improve the recovery of latent prints on evidence.