A body was found in the water near the 4 Bears Marina, next to the 4 Bears Casino, around 8 am Monday morning, according to the McKenzie County Sheriff's Office.
Several agencies responded to a report of a body floating in the water, passing under the bridge, and then continuing down the river.
Agencies waited on the shore as a boat was used to retrieve the body.
An autopsy was conducted early Tuesday morning at the State medical Examiner's office.
Law enforcement is working on identifying the individual.
The investigation has been turned over to the Three Affiliated Tribes Police Department.