Fingerprint visualization

Dusting for fingerprints can sometimes alter the prints, erasing valuable forensic clues. Now, chemists say they have developed a new fingerprint visualization technique using X-rays that leaves prints intact and, in addition, reveals chemical markers that could give investigators new clues for tracking criminals and missing persons.

Their technique was described at the 229th national meeting of the American Chemical Society, the world’s largest scientific society.

The technique could be especially promising for tracking down missing or lost children, according to the researchers. Children’s fingerprints are often more difficult to detect than adult’s. The new method could detect prints based on chemical markers left behind in the child’s fingerprints due to the presence of food, soil or saliva that can be used to track down evidence of the child’s movements, the scientists say.

Traditional fingerprinting methods involve treating samples with powders, liquids or vapours to add colour to the fingerprint so it can be easily photographed, a process called contrast enhancement. But fingerprints present on certain substances such as fibrous papers, textiles, wood, leather, plastic, multi-coloured backgrounds and human skin can sometimes be difficult to detect by this method, according to study leader Chris Worley, PhD, an analytical chemist with Los Alamos National Laboratory in New Mexico. Besides permanently altering the prints, developing an effective visualization method can sometimes be time consuming, he adds.