Oxidation monitoring by fluorescence spectroscopy reveals the age of fingermarks.

No forensic method exists that can reliably estimate the age of fingermarks found at a crime scene. Information on time passed since fingermark deposition is desired as it can be used to distinguish between crime related and unrelated fingermarks and to support or refute statements made by the fingermark donors. We introduce a non-contact method that can estimate the age of fingermarks. Fingermarks were approached as protein-lipid mixtures and an age-estimation model was build based on the expected protein and lipid oxidation reactions. Two measures of oxidation are required from the fingermark to estimate its age: 1) the relative amount of fluorescent oxidation products 2) the rate at which these products are formed. Fluorescence spectroscopy was used to obtain these measures. We tested the method on 44 fingermarks and were able to estimate the age of 55% of the male fingermarks, up to three weeks old with an uncertainty of 1.9 days.