Residues in fingerprints hold clues to their age
(PHYSorg.com Chemistry)

Police have long relied on the unique whorls, loops or arches encoded in fingerprints to identify suspects. However, they have no way to tell how long ago those prints were left behind-information that could be crucial to a case. A preliminary new study in ACS` Analytical Chemistry suggests that could change. Researchers report that they could link compounds contained in fingerprints with their age.