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Identifying tool mark and involved weapon in sharp force trauma is essential to understanding the circumstances of death. But accuracy and reliability of such expert testimony remains unknown, and validation studies are rare in forensic literature. That is why, we conducted an experiment in order to determine error rates and predictive values on identifying the right implement through different types of knife-inflicted trauma. Human bone cut marks were analysed through epifluorescence microscopy. The samples were examined through a randomised, blinded, controlled study by three researchers with varying degrees of experience with direct and indirect observation of cut marks (photography). Our results showed that identifying the weapon involved is possible thanks to numerous criteria analysis. Correct classification rates were high and misclassifications rare. Asymmetric blades obtained better results than symmetric blades. Predictive values were also calculated, and the negative one reached very high levels, near 100% with regard to all the implements. Positive predictive values were more variable. But even if individual diagnoses remain in doubt, triage can be done and tools not implicated in injury can be eliminated with certainty. Moreover, our work clearly highlighted the importance of experience in such activities. A high level of experience is fundamental to obtain the best values, especially in such a context where evidence reliability is extremely important for forensic admissibility testimony in the court.

Characteristics of sharp bone trauma can be extremely useful to determine the origin of cut marks and to provide information regarding the context of death. Using human ribs and clavicle bones, this study analyzes the characteristics of bone kerfs made by different bladed implements, thanks to epifluorescence macroscopy. This technique, which is a nondestructive tool that uses autofluorescence of bones, documents bone damage precisely with high resolution. Both qualitative and quantitative criteria are analyzed. Our results identify unique class characteristics on bone lesions, allowing modeling kerf depending on the weapon, regardless of the type of bone that is wounded. Moreover, we demonstrate for the first time microscopic criteria of directionality, using fluorescence excitation. Orientation of cracks, flakes, and lateral pushing back especially helps in determining the tip and the end of the lesion, leading to the position of the aggressor. Kerf wall characteristics and striation location are also very useful. Epifluorescence macroscopy could be a new tool of choice in anthropology through cut mark analysis in establishing how the blade was used and providing details about the blow.

Characterization of sharp-force trauma on human bones can be extremely useful in providing information regarding the nature and context of death. Nevertheless, in the identification of weapons used to cause sharp-force trauma and analysis of bone wounds, challenging tasks still remain. Current analysis attempting to dissect bone wound characteristics varied quite a lot and mixed different criteria, thus leading sometimes to conflicting results. In this context, the aim of our study is to clarify qualitative aspects of cut marks induced by sharp weapons on human bones. For that purpose, we analyzed bone samples via an original approach based on bone autofluorescence with an epifluorescence macroscope and compared it to previous existing methods. In this study, we used bone sections from human clavicles on which three different kinds of lesions were manually implemented, using different weapons. The bone wounds were analyzed by three different methodologies, light microscopy, scanning electron microscopy (SEM), and micro-computed tomography, and were compared with epifluorescence macroscopy. We paid attention more significantly to the aspect of walls and floor of the kerf, so as to conclude on the nature and distinguish between weapons used. Among all technologies used in this study, the most precise and efficient methods were epifluorescence macroscopy and SEM. Nonetheless, epifluorescence macroscopy is faster, cheaper, and more accessible than SEM. More significantly, this technique, which has the potential to accurately document the nature of the damage, is nondestructive, and could thus be highly useful in forensic science as anthropology.