John O’Neill was interned as a Prisoner of War in Southeast Asia after he was captured in South Vietnam on August 13, 1966 and was held until his death in captivity on or about September 30, 1966. He and fellow prisoner David Devers were reportedly dragged from village to village in a public display by the Viet Cong and then executed forty days after their capture. His remains were recovered and returned on January 9, 1970.