More investigation is needed to determine how Dr. John Marshall died, the Spokane County medical examiner said Wednesday.

Marshall, the chief of surgery at the Mann-Grandstaff Veterans Affairs Medical Center, went missing Monday morning after leaving the YMCA for a morning run. His body was found Tuesday in the Spokane River near the Monroe Street Bridge.

The medical examiner’s office said Wednesday that Marshall’s cause of death is “Pending further studies,” including autopsy studies and other testing.

Police tentatively identified Marshall on Tuesday based on the clothing he was wearing when he left the YMCA. They are investigating the death as suspicious.