Private First Class Koller was a member of the 23rd Infantry Regiment, 2nd Infantry Division. He was Killed in Action while fighting the enemy at "Heartbreak Ridge" in North Korea on 8 October 1951.

Koller was awarded the Purple Heart, the Combat Infantryman's 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.