On 12 September 1962, Vassall was arrested and charged with spying. He made a full confession, and directed detectives to the cameras and films concealed in his flat. The documents that he admitted to stealing did not account for everything believed to have been taken, however, which led to speculation that there was another spy still operating in the Admiralty. Some have suggested that Vassall was deliberately sacrificed by the KGB in an attempt to protect the other (possibly more senior) spy. In October, Vassall was sentenced to 18 years in jail.