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Oak Ridge National Laboratory: The Case of the Vanishing Fingerprint

Researchers at the U.S. Department of Energy's (DOE's) Oak Ridge National Laboratory (ORNL) are working with a police detective to solve a scientific mystery: Why aren't children's fingerprints as detectable as adults'?

While investigating the abduction and murder of an East Tennessee girl, Art Bohanan, a specialist with the nearby Knoxville Police Department, encountered a phenomenon he had seen before. Although witnesses saw the child enter the suspect's car, none of her fingerprints could be found inside the vehicle.

The suspect initially confessed but later recanted, making the absence of the victim's fingerprints a hurdle for the prosecution. For Bohanan, a veteran of several grim criminal investigations involving children, the case reinforced a previous observation: Kids' fingerprints don't stick around the way adults' do.

His theory was surprisingly fresh. "I couldn't find any data on the subject anywhere. I called contacts in the FBI, the National Institute of Justice, Scotland Yard, and even a police friend in Russia," Bohanan said. "Apparently no one had ever encountered or noticed the problem, much less studied it. A letter from the FBI referred to it as an area that needs to be explored."

Bohanan came to ORNL for help. After the detective met with researchers, Michelle Buchanan of the Chemical and Analytical Sciences Division began a project that, as Bohanan puts it, "could lead us to all kinds of things down the road."

Buchanan enlisted a willing group of youths, ages 4 to 17, to shake vials of alcohol between their thumb and forefinger to collect chemicals from their skin. She also took similar samples from adults, ages 19 to 46. In Buchanan's lab, tests on the samples using gas chromatography/mass spectrometry, which is a very sensitive method of analyzing and identifying chemicals, appear to bear out the detective's hunch: Kids' fingerprints are different.

"We see a marked difference in the chromatograms," Buchanan said. "Children's fingerprints contain more volatile chemicals, such as free fatty acids, while adult prints display longer lasting compounds."

Knowing the chemical difference in adults' and children's fingerprints is likely to lead to a test for latent juvenile fingerprints. Buchanan said that after her organic mass spectroscopy group identifies the compounds in the prints, another ORNL researcher, Tuan Vo-Dinh of the Health Sciences Research Division, could be asked to try to come up with a method for detecting kids' prints. Vo-Dinh has developed numerous optical technologies, including improved methods for testing for polychlorinated biphenyls, or PCBs, a significant pollutant, and a laser-based, nonsurgical technique for cancer diagnosis and treatment.

The fact that the gas chromatographic profiles identified so many chemicals present in the skin has Buchanan theorizing that this research could lay the groundwork for new noninvasive diagnostic procedures. "It has been reported that a number of compounds present in the skin's surface are indicators of some diseases," Buchanan said. "We hope to improve sampling techniques to develop new methods to detect target compounds that can tell us more about what's going on inside the body."

In the meantime, an enthusiastic Detective Bohanan envisions what his police work could lead to. "I'd like to see one-touch patch tests for drugs so that we could detect them at the scene. Forensic evidence is often lost or tainted because of delays in analysis or accidents along the way," Bohanan said.

ORNL, one of DOE's multiprogram research laboratories, is managed by Martin Marietta Energy Systems, Inc., a Lockheed Martin company, which also manages the Oak Ridge Y-12 Plant and the Oak Ridge K-25 Site.