Researchers from the National Institutes of Standards and Technology (MD, USA) have reported a novel method for analyzing fingerprints. Their study, recently published in Analytical Chemistry, outlines how they used mass spectrometry to determine how old fingerprints are, which could be a vital development for forensic investigations.
We have long had the means to identify fingerprints at crime scenes. Information such as the owners’ age and gender can be gleaned from them, helping to solve many cases and convict criminals. Age dating them, however, remains a major challenge. The ability to reliably assess the relevance of these unique identifiers would allow investigators to rule suspects in or out, based on when they are from. This would therefore have a significant impact on forensic science and judicial proceedings.
After determining the chemical composition of a fingerprint, the team used time-of-flight secondary ion imaging mass spectrometry to measure the diffusivity of saturated fatty acid molecules over known time frames. They focused on palmitic acid in particular, and were able to obtain an equation to calculate its position in millimetres as a function of time in hours. The published results demonstrate that the technique can reliably determine the age of fingerprints up to 4 days old.
The scientists noted that the fingerprints are currently being analyzed under ideal lab conditions on silicon wafers; however, future studies will focus on samples in a variety of settings. Edward Sisco, one of the study authors, commented: “Once we see it’s feasible, we’ll move onto more realistic […] exposures.”
Sources: Muramoto S, Sisco E. Strategies for potential age dating of fingerprints through the diffusion of sebum molecules on a nonporous surface analyzed using time-of-flight secondary ion mass spectrometry. Anal. Chem. 87(16), 8035–8038 (2015); A new CSI tool could pinpoint when fingerprints were left behind.