Application of forward-looking infrared (FLIR) imaging from an unmanned aerial platform in the search for decomposing remains

Abstract

Traditional methods of cadaver detection in outdoor environments include manual ground search, cadaver dogs, and manned aerial reconnaissance during daylight. These methods have limitations; however, a potential low-cost alternative may be to employ thermal imaging equipment mounted on an unmanned aerial vehicle (UAV) to detect heat emitted by insect and bacterial activity on the decomposing remains. No studies have addressed the influence of wrappings on detection of maggot mass thermal signatures nor assessed thermal detection of smaller body fragments. We addressed these knowledge gaps by utilizing a two-phase experimental approach to explore thermal detection of carcasses using UAV-mounted infrared imaging. In Phase 1, pig body fragments were deposited on the surface or shallow buried. In Phase 2, whole pig carcasses were deposited in four conditions: on the surface uncovered, wrapped in plastic or carpet, or buried. Our results demonstrated that observable heat emissions from remains corresponded to peak insect activity during active decay and could be readily detected in uncovered whole carcasses and fragments. Although plastic and carpet wrappings partly impeded detection of insect heat signatures, these materials were clearly detectable themselves because of their contrast to the background ground surface. Thermal signatures of buried partial remains and disturbed gravesoil were also observed; however, the buried whole carcass transitioned to adipocere prior to the decay stage and without any insect colonization or heat signature. These data can inform operational implementation of this technique to complement existing search strategies to offer a robust, low-cost alternative for use where scene characteristics allow.