Forensic Summary by Gina Gallucci
Fingerprints found at crime scenes are often contaminated by various substances. The most common of these is blood, especially at violent crime scenes. Current techniques involve chemical presumptive tests to confirm the presence of blood that can yield false positives and may contaminate the print, affecting the recovery of DNA for analysis. Other methods such as blood typing or alternative light sources are both destructive to the print and to the DNA that may be present. An ideal technique that allows for the detection of blood would be non-destructive without contact and should be highly sensitive to low levels of blood and highly specific so as to avoid false positives.
A visible wavelength hyperspectral imaging (HSI) method that focuses on the Soret γ band absorption in hemoglobin between 400 and 500 nm was proposed. It is non-contact and non-destructive while also focusing on ridge detail. The study utilized human and horse blood. Six and twelve depletions series of horse and human blood, respectively, were assessed on white ceramic tile. Other contaminants were also used to compared the ability of HSI to distinguish blood from other visually similar contaminants. After analysis, HSI successfully determined blood from non-blood contaminants. There were zero false positives.
Cadd, Samuel, Bo Li, Peter Beveridge, William T. O’Hare, Andrew Campbell, and Meez Islam. “The Non-contact Detection and Identification of Blood Stained Fingerprints Using Visible Wavelength Reflectance Hyperspectral Imaging: Part 1.” Science & Justice 56.3 (2016): 181-90. Web.