Distinguishing thermally altered bones from debris using imaging and fluorescence spectrometry

Bushfires and mass disasters from which result fatal fire victims are two types of events in which Forensic Anthropology acts aiding in the recovery of human remains and the identification of the victims. This is a challenging job since bones that have undergone fire-caused alterations can be unrecognizable. Therefore, collecting evidence at the scene is very important and should be thorough. To evaluate the potential of the application of optical techniques for the recovery and analysis of burnt skeletal material in forensic contexts, this exploratory study focused on analysing reflectance and luminescence properties of bone to differentiate between skeletal remains and debris. The sample includes burnt human bones, as well as non-human bones and debris (like metal, fabric, and others). The reflectance experiments revealed to be quite ineffective, not showing a response pattern that allowed for discrimination between skeletal remains and debris. Three techniques were used to detect luminescence, which included imaging (with a camera), fluorescence spectrometry, and laser-induced fluorescence spectroscopy (excitation: 440 nm). Luminescence results were more promising, registering a positive response for several samples, with a general consistency of results between the different methodologies. Nevertheless, burning conditions and individual characteristics (e.g., pathologies) can introduce limitations to the techniques.