RAPID CITY, S.D. (KELO) — Authorities have identified the man whose body was found in a water drainage tunnel in Rapid City.

Rapid City Police say after the body of Duane Yellow Cloud, 52, was found Sunday morning near East Boulevard and Omaha Street, an autopsy was performed. It revealed no evidence of traumatic injury.

As they investigated, police found evidence the water drainage tunnels have been used as shelter by the city’s homeless population. It is believed Yellow Cloud was using the tunnel as shelter when he died.

Police say his heavy clothing indicates he died during the winter months and they think recent heavy rains likely swept his body to the gated runoff tunnel.

In December, police reported Yellow Cloud was missing. He was last seen on December 16, 2022.

“There is no way to describe this situation as anything but tragic, and the collective sympathies of the RCPD go out to Mr. Yellow Cloud’s family and friends in the wake of his passing,” the police department shared on Facebook.