The cause of death has been released in the case of a Billings man whose body was found north of Butte in May.

Autopsy results indicate Aaron O'Shea, 31, died from blunt force trauma to the head, Butte-Silver Bow Coroner Lee LeBreche said.

O'Shea sustained a fracture to the skull, but the cause of the fracture is undetermined, LeBreche said.

O'Shea was in Butte to check into the Montana Chemical Dependency Center, LeBreche said. He was 30 years old when he was last seen near the bus transfer center area next to the Butte Civic Center on January 14. A bag belonging to him was found in the North Excelsior Street area on January 15.

It wasn't until months later that his body was discovered off of Frog Pond Road in the Bull Gulch area north of Walkerville. A person driving a four-wheeler on the evening of May 19 discovered O'Shea's body.

Fingerprint records led to a positive identification of the body, LeBreche said.

O'Shea has family in the Bozeman area.

Police continue to investigate the case.