Dating bloodstains with fluorescence lifetime measurements

In summary, fluorescence lifetime was shown to be a promising technique to evaluate the age of a bloodstain in a crime scene within the first week. The method is fast (ca. 20 min), reproducible, concentration independent, and requires a miniscule amount of the bloodstain with minimal sample preparation. The major improvement of the technique will come from the development of the lifetime imaging technique, in which the average fluorescence lifetime is evaluated across the region of interest in the bloodstain. Such an approach will minimize the problems with sampling and provide more accurate results. The measurements can potentially be performed in solid state by using a handheld fluorescence-lifetime instrument, which could be applied to the bloodstain directly at the crime scene with no additional sample handling.