A new CSI tool could pinpoint when fingerprints were left behind

Law enforcement officials have long relied on fingerprints left behind by criminals to help solve cases. In addition to patterns of whorls, loops and arches specific to individuals, prints can also yield clues as to the owners' age and gender, as well as materials -- such as explosives or make-up -- that they may have touched. But determining just how long these residues have been at a crime scene is one aspect that has remained a challenge. The ability to date fingerprints would allow police to more easily rule certain suspects in or out of their investigations. Shin Muramoto and colleagues wanted to find a way to meet that need.

The researchers studied various molecules in fingerprints and found that a substance called palmitic acid migrates away from print ridges at a predictable rate. Based on this diffusion, the scientists could estimate how old a fingerprint was. Their findings apply to prints up to four days old, but they plan to expand that window to 10 days.