Sergeant First Class Keller was a member of Company K, 3rd Battalion, 8th Cavalry Regiment, 1st Cavalry Division. He was taken Prisoner of War while fighting the enemy near Unsan, North Korea on November 2, 1950 and died while a prisoner on July 31, 1951. His name is permanently inscribed on the Courts of the Missing at the Honolulu Memorial. SGT Keller's remains were recovered and identified in 2014.