Solving a cold case through scientific evidence

What role can a rigorous methodological approach play in establishing scientific evidence? This study examines the death of a 36-year-old homeless man in Northern Italy in the late 1990 s. Found unconscious with signs of assault, he was hospitalised in a coma with facial trauma. A brain CT scan showed multiple contusions and a subarachnoid haemorrhage. Due to his condition, he was transferred to another hospital, where he died shortly after. The forensic autopsy, based on the presence of purulent material and leukocytic infiltration in the brain, identified cardiorespiratory failure due to meningoencephalitis as the cause of death, excluding any link to the assault. However, the case was suspended due to the suspects’ absence, and the judge did not examine the forensic findings. In 2017, the investigation was reopened after identifying a suspect. The reanalysis of histological samples confirmed subarachnoid and intraparenchymal haemorrhages with leukocytic infiltration in the haemorrhagic areas. A broader macro- and microscopic analysis of the formalin-preserved brain revealed a similar pattern, with minimal leukocytes mixed with red blood cells in the meningeal spaces. Immunohistochemical analysis using CD15 antibody showed leukocytes only in haemorrhagic areas. The cause of death was thus redefined as traumatic subarachnoid haemorrhage, excluding meningoencephalitis. This case demonstrates the importance of a rigorous evidence-based methodological approach in establishing scientific evidence. Integrating techniques such as immunohistochemistry allowed for accurate cause-of-death identification nearly 20 years later, highlighting the value of scientific rigour and multidisciplinary collaboration in forensic medicine.