A fatal case of Munchausen syndrome by proxy in the father-daughter dyad.

Factitious Disorder Imposed on Another (FDIA), formerly known as Munchausen Syndrome by Proxy, is a rare form of abuse where parents induce or fabricate symptoms in their child, exposing them to unnecessary and potentially harmful medical treatments. In over 90% of cases, the perpetrators are mothers. A father was put on trial for the murder of his three-month-old daughter and was eventually convicted of repeatedly inducing respiratory crises, ultimately causing her death. Investigations began after multiple visits to the Emergency Department for respiratory episodes reported by the father but not confirmed by physicians: the attending paediatrician first hypothesized FDIA. A medico-legal autopsy excluded diseases justifying prolonged hospitalization or independently causing death; the only relevant post-mortem findings were massive pulmonary congestion with minute subpleural petechiae and hemosiderin-laden intra-alveolar macrophages, indicating nonspecific acute respiratory failure. Forensic psychiatric evaluation of the father revealed a rigid personality, excessive conformity and interpersonal immaturity. Publicly, the father appeared caring and deeply involved with his daughter. He exhibited a propensity to develop somatic symptoms and a tendency towards reality distortion. These traits aligned with FDIA, later confirmed by judicial reconstruction of events. The multidisciplinary approach led to the establishment of the judicial truth: a case of paternal infanticide by asphyxiation. In Italy, FDIA is not a mental illness excluding criminal responsibility, though the diagnosis may influence sentencing. The first-instance judgment classified the act as preterintentional homicide, considering Munchausen by proxy. The final verdict, however, convicted the father of intentional homicide. This case highlights the intrinsic diagnostic dilemma at the clinical–forensic interface, where psychiatric assessment and judicial interpretation may align or diverge, underscoring the need for caution in translating psychiatric diagnoses into legal conclusions.