A Reflective Spectroscopy Proof-of-Concept Study of Urea for Supporting Investigations of Human Waste in Multiple Forensic Contexts

Human urine and its detection are of interest in forensic studies in numerous contexts. Both crystalline urea and 1.0 M solutions of urea, as synthetic analog endmember components of human urine, were investigated as a proof-of-concept study to determine if detailed lab spectroscopy would be viable. Urea was reliably detected on Ottawa sand at concentrations of approximately 3.2% in dried experiments. Urea was detectable after 1 week of solution evaporation under lab conditions, at 9.65 wt.% 1 M solution. This investigation successfully establishes urea as a material of interest for reflective spectroscopy and hyperspectral remote sensing/image spectroscopy on a wide range of spatial scales, from specific centimeter-scale areas in a crime scene to searching large outdoor regions > 1 km2. In addition, this investigation is relevant to improving the monitoring of human trafficking, status and condition of refugee camps, and monitoring sewage.