Corporal Costello was a Jeep driver with Company A, 1st Battalion, 17th Infantry Regiment, 7th Infantry Division. He was Killed in Action while on a combat patrol to investigate guerrilla activity near Tanyang, South Korea on 3 January 1951.

Costello 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.