Fingerprints may have changed the game in police work since they were first used more than a century ago, but they still have a weak spot: Detectives can't tell precisely when they were left, per ScienceDaily. Generally, police can tell if a print has been left within the last week, but they can't pinpoint it any closer than that. Now, a study out of Iowa State University in Analytical Chemistry suggests things are about to change. Researchers had three volunteers leave prints on glass slides over the course of a week, and the scientists were later able to determine which day the prints were left, reports New Atlas. The key? They focused on the degradation of certain oils in the fingerprint.
Specifically, the researchers zeroed in on how ozone in the air interacts with unsaturated triacylglycerols left in the print, explains the Economist, which goes into much more detail on the scientific process. This kind of analysis doesn't harm the print and can be conducted even after forensic dusting has taken place. One challenge, however, is that researchers discovered the rate of degradation seems to be different for each person, meaning police might not be able to date a print unless they knew who it was from. More research is needed, but the scientists see these results as a major step forward. The bottom line: If a print is less than a week old, police might soon be able to determine its age within 24 hours. (Read more fingerprints stories.)