Private First Class Custer was a member of Company I, 3rd Battalion, 179th Infantry Regiment, 45th Infantry Division. He was Killed in Action while fighting the enemy in North Korea on 12 May 1952. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.

Custer was awarded the Purple Heart, the Combat Infantryman 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.