A series of asphyxiation cases in confined spaces: forensic investigation into the involvement of plastic bags and gas inhalation

Introduction: In forensic science, confinement of the head within a plastic bag suffocation (PBS) combined with inhalation of volatile substances represents an uncommon but highly challenging scenario, particularly in determining the cause and manner of death. Materials and Methods: A retrospective analysis was conducted, including all 28,802 autopsies performed in Milan from 1993 to 2024. Twenty-eight cases of death due to PBS associated with inhalation of different gases (nitrogen, propane-butane mixtures, helium, propane, and butane) were identified. For each case, circumstantial data, autopsy findings, and toxicological and histological analyses were systematically reviewed. Results: Over a period of more than 30 years, this phenomenon predominantly involved young individuals from different social backgrounds and occurred in both suicidal and accidental contexts. In several cases, individuals appeared to use this method not only for suicide but also for recreational purposes, under the mistaken belief that gas inhalation could be controlled; however, rapid loss of consciousness often prevented any corrective action. Overall, 17 cases were classified as complex suicides, 5 as accidental deaths, and in 6 cases the manner of death remained undetermined. No cases were attributable to autoerotic practices or assisted suicide. Discussion: PBS combined with gas inhalation represents a multifactorial and highly lethal mechanism of death, often characterized by nonspecific autopsy findings and significant diagnostic challenges. Conclusions: These findings emphasize the critical importance of thorough scene investigation and contextual analysis, as removal of the plastic bag and the limited specificity of forensic findings may hinder accurate determination of the manner of death.