“Rust stain”: a rare mark in firearm suicide—a case report and review of the literature

Rust stains are marks left by firearms in case of prolonged contact with the cutaneous surfaces. These peculiar signs along with other well-documented findings can guide the medical examiner in the determination of the manner of death, especially in case of firearm suicide. This paper presents the case of a 33-year-old male soldier who committed suicide by using a short-barreled weapon, whose trigger remained in contact with the first finger of his right hand, leading to the formation of a rust stain that perfectly reproduced its design. The forensic examination of the scene, the external cadaveric inspection, and the autopsy are described. For the evaluation of the histological findings typical of rust spots, the authors decided to replicate the phenomenon in an experimental setting using porcine skin. In order to provide an exhaustive overview on the formation and the features of rust stains, a review of the forensic literature concerning this rare mark was performed.