Sergeant Gruetzner was a medic with the Medical Detachment, 2nd Engineer Combat Battalion, 2nd Infantry Division. He was seriously wounded by the enemy in South Korea on 3 September 1950 and returned to duty later that day. He was listed as Missing in Action while tending his wounded comrades near the Chongchon River in North Korea on 27 November 1950. He was presumed dead on 31 December 1953. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Gruetzner was awarded the Purple Heart with Oak Leaf Cluster, the Combat Medical Badge, the Korean Service Medal, the United Nations Service Medal, the National Defense Service Medal, the Korean Presidential Unit Citation and the Republic of Korea War Service Medal.