Detection of fresh blood by luminol and DNA after walking over various substrates

Abstract

This preliminary research aimed to determine if a forensically useful human DNA profile could be obtained from latent blood past the point at which the blood could be visualized with luminol. Five participants with differing physical characteristics created shoeprints from fresh human blood over concrete, linoleum and carpet. The amount and distribution of both visible blood and chemiluminescence emanating from latent blood were documented. DNA analysis was performed on samples taken from the fifth last latent shoeprint to show chemiluminescence and the first and tenth steps after which chemiluminescence no longer occurred. DNA from the blood source was obtained past the point of visualization using luminol, with 2 of the 30 samples generating full STR DNA profiles, 18 generating partial profiles of 4 or more alleles, and 3 generating between 1 and 3 alleles. Of the 7 samples which did not generate a profile, 6 came from the concrete. Higher amounts of DNA, and more full and partial profiles, were obtained from linoleum compared to concrete or carpet. Participant effect was not observed. These findings demonstrate that it may be possible to obtain forensically useful DNA from crime scenes even when blood is not able to be visualized with chemiluminescence.