Corporal Ollero was a member of Company C, 1st Battalion, 19th Infantry Regiment, 24th Infantry Division. He was taken Prisoner of War while fighting the enemy in South Korea on July 16, 1950, forced to march to North Korea on the "Tiger Death March", and died while a prisoner at An-Dong, North Korea on May 23, 1951. His remains were not recovered. His name is inscribed on the Courts of the Missing at the Honolulu Memorial.