Sergeant First Class Koon was a medic with the Medical Company, 9th Infantry Regiment, 2nd Infantry Division. He was taken Prisoner of War while tending his wounded comrades in North Korea on December 1, 1950 and died while a prisoner on April 30, 1951. His remains were recovered in 2002 and identified April 15, 2008. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.