verify her own background – and to look for anything that would invoke suspicion. "They found nothing out of the ordinary." Bentley had learned how to dodge such intrusions from her earliest days in the underground: She learned how to determine if enemy agents had discovered secret documents in her possession. "If I had to leave the apartment, I was careful to put them in my black trunk and tie a thin black thread around it so that I would know if they had been tampered with in my absence." The CIA has used black bag operations to steal cryptography and other secrets from foreign government offices outside the United States. The practice (by preceding U.S. intelligence organizations) dates back at least as far as 1916. Black bag operations in popular culture Sam Fisher (Splinter Cell) Sombra (Overwatch) The Doorbell Rang See also Black operation COINTELPRO Elizabeth Bentley Parallel construction References General references Wright, Peter, Spy Catcher: The Candid Autobiography of a Senior Intelligence Officer. Penguin USA, 1987. . Inline citations Bibliography External links "11 Terms Used by Spies". HowStuffWorks. Cryptographic attacks Federal Bureau of Investigation operations Intelligence operations by type