A REFLECTIVE SPECTROSCOPY ANALYSIS OF HUMAN BLOOD FOR THE SUPPORT OF POLITICAL VIOLENCE INVESTIGATIONS THROUGH HYPERSPECTRAL REMOTE SENSING

The emerging use of airborne, handheld, and stationary hyperspectral imaging and reflective spectroscopy techniques to investigate violent crimes and crimes against humanity including human trafficking, and mass deportation efforts is developing rapidly. One key step in improving overall accuracy in interpretation of materials and scenes is creating and augmenting existing spectral libraries using the most relevant materials. One ubiquitous material associated with violent crimes is human blood. Human blood is a prevalent material that is found in association with materials such as clothing and soils, which are items that can be detected through hyperspectral imaging and reflective spectroscopy techniques. As part of ongoing efforts to improve an existing database for hyperspectral imaging and reflective spectroscopy, this investigation evaluated reflective spectra of human blood on representative geological materials and some selected clothing items. The initial efforts focused on evaluating changes in spectra over the period of one week to establish age estimations of blood. Human blood has several distinct features that could be observed on geologic and clothing substrates investigated and there are systematic changes observed in the laboratory setting. Limitations are expected in distinguishing blood on red backgrounds such as iron oxide/oxyhydroxide-rich soil or materials with high water content. Next steps in the study include expansion of evaluation of data on other geomatieral substrates and clothing over the one week time period, followed by evaluation of data on selected items with aging times of 10+ weeks. Results suggest the ability to identify blood through IS/HRS and a path for developing age estimations, however, variables including the ecological nature of substrates, temperature, and intensity of solar illumination must be examined further in future work. These efforts are applicable to numerous settings of violence globally, but also serve as a basis for developing quantitative tools to support remote sensing of political violence of a variety of scales ranging from individual hostage event scenarios to major conflict and genocide.