This case documents a rare occurrence of heterotopic mesenteric ossification (HMO) identified at autopsy, highlighting the long-term sequelae of prior abdominal trauma and expanding awareness of this uncommon entity in forensic pathology. HMO, also called intraabdominal myositis ossificans, is a subset of myositis ossificans traumatica and is characterized by the abnormal formation of osseous, cartilaginous, and sometimes bone marrow elements. It is generally associated with trauma or previous abdominal surgeries and can lead to potential life-threatening complications. Autopsy findings may highlight the presence of extensive ossified tissue formation in the mesentery, along with signs of the associated complications. Due to the rarity of these findings, the diagnosis at autopsy is challenging. In the present case report, the body of a 34-year-old Black male who died of multiple gunshot wounds was examined at the Cook County Medical Examiner’s Office. He had a history of remote abdominal multiple gunshot wounds with subsequent exploratory laparotomy. During the post-mortem examination, dense fibrous adhesions were noted in the abdominal cavity and multiple fragments of ossified tissue were removed from the mesentery. The observed findings were suggestive of HMO. Radiological imaging can reveal early ossification within weeks of trauma, while histopathological analysis confirms the diagnosis, showing mature lamellar bone with minimal atypia. This case highlights the importance of recognizing and considering this rare entity in the differential diagnosis when no apparent causes of death are detected at autopsy.