Reverse engineering in forensic investigations: a new approach to bite mark analysis

The study of bite marks provides crucial elements that contribute towards identifying the biter. In many cases, it assumes importance when bite marks are detected on the body of a victim of violence, but it could also be relevant when the bite marks are seen on food substances at the crime scene. In both circumstances, comparing the bite marks with a suspect's dentition can be decisive in confirming or excluding the culpability. In this case report, a bun (bread roll) with the sign of a bite was found at the crime scene. We report a pilot study using 3D reproduction of the bite mark on the bun and dental models of the alleged biter and the victim. A reverse engineering process was used to obtain digital 3D models of the bitten bun and the dental models by taking numerous photographs and stitching them together using a software called Metashape by Agisoft. The last step was to compare the bitemark to the two dental models, evaluating the spatial distance, the degree of overlap, and the degree of interpenetration. The results confirmed the usefulness of reverse engineering in forensic investigations showing the compatibility between the victim's teeth and the bite mark on the bun.