Gordon Mason's quarry, a wily teenage fascist spy named Carla Costa, was said to have been the best female agent working for the Germans in Italy.
She had not yet turned 17 when she ran away from her home in Rome during World War II and joined a cadre of Italian spies organized to aid German military intelligence.
She proved so skilled at carrying messages to and from enemy territory that she received an audience with Benito Mussolini at his northern headquarters near Lake Garda, where he lauded her.
Mason died April 3 at 98 from congestive heart failure in Warrenton, Va., his family said.
He was in his late 20s during the war and was serving in the Army Counterintelligence Corps (CIC). The son of Italian immigrants, he spoke Italian fluently and was tasked with arresting Costa before she could further damage the Allied cause.
With information gathered from a fascist agent in custody, his unit closed in on Costa in October 1944 near the Tuscan town of Pistoia.
Mason was following her presumed route and spotted her on a bicycle.
He detained Costa and brought her back to his station for questioning, according to an account by British historian James Holland in the book "Italy's Sorrow: A Year of War, 1944-1945." The Americans quickly discerned that they had met a formidable opponent.
"Despite her youth and sex," reads a Counterintelligence Corps report cited by Holland, Costa "has proven herself the most stubborn and tenacious enemy agent or suspect whom CIC, 5th Army, has encountered in the course of its work in Italy."
Costa ultimately was released, her youthful spunk having earned a sort of admiration from her captors.
In the CIA after the war, Mason served in positions that included chief of external operations for the Soviet bloc and station chief in Romania, Ghana, Holland and Ethiopia, according to his family.
He later held high-ranking positions at the CIA headquarters. Before Mason retired in 1977, CIA Director George H.W. Bush awarded him the Distinguished Intelligence Medal.