Micro-CT-based virtual reconstruction of a kerf-like defect in a partially severed human clavicle: a case report

We report a forensic case in which micro-computed tomography (micro-CT)-based three-dimensional (3D) registration of partially severed human clavicle fragments provided additional morphological context for interpreting skeletal toolmarks. Conventional stereomicroscopic examination of the cleaned cut surfaces revealed crossing and overlapping striations that superficially resembled reciprocating saw marks and were difficult to interpret in isolation. The registered micro-CT models exhibited an acute, V-shaped, kerf-like profile with a maximum apparent penetration depth of 7.3 mm. A Python-based cross-sectional angle measurement workflow generated 20 profiles along the visually defined valley of the kerf-like defect, of which 17 were measurable, yielding a mean internal profile angle of 9.07° ± 1.94° (range 5.82°-12.56°). Surface deviation mapping visualized cortical apposition and separation across the registered fracture interface, supporting the interpretation of a morphologically coherent kerf-like cavity, although registration-related effects could not be fully excluded. Multiple shallow straight marks adjacent to the main defect were consistent with false-start-like lesions, although not independently diagnostic of a specific tool class. The 3D morphology and descriptive measurements provided spatial context for evaluating the ambiguous surface striation patterns but were not treated as validated criteria for tool-type identification. This interpretation was broadly consistent with subsequent investigative information, regarded as contextual consistency rather than independent validation. This case suggests that micro-CT-based virtual registration may provide additional morphological context when surface striation patterns are ambiguous; however, systematic experimental validation is required before broader forensic application.