Reflective spectroscopy of African migrant clothing for humanitarian and forensic investigations

Hyperspectral remote sensing/image spectroscopy (HRS/IS) has increasingly been utilized in forensic and humanitarian contexts, where spectral signatures aid in the location of human remains, identification of disturbed terrain, and detection of materials indicative of criminal activity. During forensic and humanitarian investigations, articles of clothing are essential pieces of evidence when employing HRS/IS techniques, as clothing remains the dominant material exposed to aerial, space-based, or unmanned monitoring systems. In this study, thirty-nine articles of clothing were collected from African migrants in temporary camps at known points of origin in North Africa and analyzed using an Analytical Spectral Devices (ASD) (PANalytical) FieldSpec 4 Hi-Res spectroradiometer and scanning electron microscope (SEM). The observed fabric types include cotton, polyester, elastane, and rayon, which varied in size, style, color, pattern, shape, and condition. Results show multiple distinct absorption features in the NIR and SWIR spectral ranges for endmember and blended fabric compositions, which can be easily distinguished through remote sensing techniques. Additionally, when affected by environmental debris, SEM analysis indicates the known amount of material found on a garment does not obscure reflective spectra. Results from this study show HRS/IS techniques are effective in lab-based settings with material evidence and enhance the suitability of in-field data collection, leading to the potential for remote crime scene investigation.