The Use of Near-Infrared Remote Sensing in the Detection of Clandestine Human Remains
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Most commonly, searches for clandestine remains have utilized time-consuming methods such as line searches that require the support of many individuals to scour a typically large area. While these methods do yield results, they take time to execute, and in certain places may actually prove dangerous for the participants. Many additional methods have been tested and utilized in the recovery of human remains, including the use of metal detectors, aerial photography, and ground-penetrating radar, which can be time consuming and expensive. Only in recent years has the use of near-infrared imagery been experimented with as a means of uncovering clandestine graves and surface remains. As human remains decompose, a large amount of organic matter enters into the surrounding soil, forming a cadaver decomposition island (CDI). Because soils that are organically rich have a different reflectance signature than nearby unaffected soils when viewed with near-infrared (NIR) imaging, it is likely that by using NIR photography and drone technology, clandestine remains may be recovered more quickly and more efficiently than has previously been possible. Because NIR photographs can be obtained using small, remotely controlled aircraft or aerial drones, large areas can be surveyed for clandestine remains remotely, thereby minimizing the need to involve a substantial group of people in the search. In so doing, potentially dangerous locations can be searched without great risk, disturbances to forensically significant sites will be minimized, and the area that personnel must search will be reduced and more precisely understood. The present study explores the utility and longevity of near-infrared cameras mounted to Unmanned Aerial Systems (UAS) in the detection of clandestine human remains deposited on the surface. Aerial NIR photographs and soil samples were compiled from 104 identifiable CDIs (i.e., the fertile soil area below and surrounding a decomposing cadaver) at the Forensic Anthropology Research Facility at Texas State University in San Marcos, Texas. Results indicate that CDIs have a unique NIR spectra signature that can be successfully utilized to find clandestine remains.