REFLECTIVE SPECTROSCOPY STUDY OF BLOOD ON GEOLOGIC AND OTHER MATERIALS: PROVIDING FORENSIC CONTEXT FOR OUTDOOR CRIME SCENES
Two distinct substrate types were chosen, representative of a broad range of possible geographic areas within North America. Reflective spectroscopy analysis of blood on both of the sediment types was performed multiple times and averaged at 10 distinct periods of elapsed time, ranging from 1-144 hours, beginning when the blood first came into contact with the sediments. Graphs representing reflectance and corresponding wavelengths were generated for both sediment types at each of the 10 time periods. Unique absorption features relating to blood, such as Fe3+, were identified on each of the graphs. Changes in the detectability of certain absorption features relating to blood using reflective spectroscopy over this time period were documented.
This analysis provides frames of reference for future forensic investigations, utilizing reflective spectroscopy analysis of blood on similar geologic substrates, to assist in blood detection and aging. Using methods such as hyperspectral remote sensing, blood evidence can be found and documented in areas that would otherwise be difficult to gain access to, such as denied areas, countries, or ambiguous political borders. Further investigations into reflective spectroscopy detection and aging of blood on increased varieties of geologic material will provide greater context for future forensic investigations worldwide.