The working titles of this film were Operation Cicero and Five Fingers. According to a SatRev article on the picture, the title was changed to 5 Fingers "to avoid any association with the recent race riots in [Cicero] Illinois." Before the film's opening credits, a written statement reads: "This is a true story. All the exterior scenes in this picture were filmed in the locales associated with the story." Also before the title card, there appears a sequence set in the British House of Commons on 18 Oct 1950, at which time the publication of the book Operation Cicero by L. C. Moyzisch is discussed. The actor playing the Foreign Secretary acknowledges that the espionage story is true and that the mysterious "Cicero" sold vital secrets to the Germans. Intermittent narration describing the action is heard throughout the film, and at the picture's end, another written statement reads: "20th Century-Fox Film Corporation wishes to express sincere thanks and appreciation to the government and the people of Turkey for their generous cooperation during the filming of the exterior scenes for this picture."
       5 Fingers is loosely based on the life of Elyeza Bazna (1905--1971), the valet to the English ambassador to Turkey during World War II, Sir Hughe Knatchbull-Hugessen. [Bazna's name is spelled several different ways by both contemporary and modern sources.] Between Oct 1943 and Feb 1944, Bazna photographed a large number of top secret documents from the ambassador's safe and sold them to the Germans. L. C. Moyzisch, the author of the book on which the film is based, was a military attaché at the German Embassy in Ankara and the contact for Bazna, who was given the code name "Cicero" by the Germans. Despite the genuine nature of the documents supplied by Bazna, as shown in the film, jealousies between high-ranking German officials prevented them from being used. The Germans were also afraid that Cicero was a British counter-intelligence agent. Bazna, who received £300,000 from the German government and was called "the highest paid spy in the world," was paid mostly in counterfeit British pounds that had been printed in Germany. As in the film, Moyzisch's book was discussed in the British House of Commons, at which time the foreign secretary proclaimed that measures had been taken to prevent such an occurrence from happening again.
       According to a 30 Oct 1950 LAT article, after the incident in the House of Commons, a number of film studios and producers were interested in obtaining the rights to Moyzisch's book, including Arthur J. Rank, Alexander Korda and M-G-M. Modern sources report that Henry Hathaway was originally scheduled to direct the picture before Joseph L. Mankiewicz became interested in Michael Wilson's adaptation of the book. According to the Twentieth Century-Fox Records of the Legal Department, located at the UCLA Arts--Special Collections Libary, Mankiewicz worked extensively on the screenplay, but modern sources report that he agreed to forego onscreen credit for his contribution to the screenplay in exchange for being allowed to direct the project. Studio records indicate that Fox also purchased a magazine article about Bazna entitled "The Highest Paid Spy in History" by Robert M. W. Kempner (The Saturday Evening Post, 28 Jan 1950) in order to protect its rights in regards to Bazna's story. Kempner's article was not used in the preparation of the screenplay for 5 Fingers, however.
       According to a 2 Aug 1951 HR news item, Micheline Prelle was originally signed for the role of "Anna" (which was fictional, unlike the majority of the other characters in the film), but had to withdraw from the cast due to pregnancy. Although some contemporary and modern sources refer to Michael Rennie's character as "George Travers," he is called "Colin Travers" in the film. The CBCS lists both Frank Hemingway and John Sutton as the film's narrators, but only Sutton was heard in the viewed print. As noted in the onscreen credits, the exterior sequences in the film were shot on location in Ankara and Istanbul, with doubles being used for the principal actors. According to a Jul 1951 Var article, while shooting on location, Mankiewicz was warned that "he would not be permitted to bring his camera crew into the British Embassy grounds--and that any exterior shots, even with telephoto lenses, would be regarded as an unfriendly act." While filming in Turkey, Mankiewicz met the real Bazna, according to an Apr 1952 Life article. The article also noted that Bazna's offer to serve as a technical advisor on the film was turned down. Studio records report that Moyzisch's offer to act as a technical advisor for the film also was refused, and that after the picture's release, Moyzisch was very displeased by the depiction of him and requested that his name be taken off the credits.
       On 13 Sep 1951, HR reported that writer Michael Wilson had been subpoenaed by the House Committee on Un-American Activities and was subsequently laid off from Twentieth Century-Fox. Following Wilson's testimony before the committee, during which he refused to confirm or deny membership in the Communist party, he was blacklisted and received only one onscreen credit, for the 1954 film Salt of the Earth (see below), until 1965, when he received credit for The Sandpiper. Wilson did contribute to a number of other screenplays, including Lawrence of Arabia, but did not receive onscreen credit for them.
       For their work on 5 Fingers, Mankiewicz received an Academy Award nomination for Best Direction, and Wilson received an Academy Award nomination for Best Screenplay. The film, which garnered excellent reviews, was named one of the ten best films of 1952 by NYT and FD. Lux Radio Theatre broadcast two versions of the story, both of which starred Mason and his wife, Pamela Kellino. The first show aired on 13 Oct 1952, and the second was broadcast on 1 Feb 1955. The 20th Century-Fox television program broadcasted a version of the story, entitled Operation Cicero, in Dec 1956. The one-hour telefilm was directed by Hubert Cornfield and starred Ricardo Montalban and Maria Riva. From 3 Oct 1959--6 Jan 1960, the NBC television network ran a series very loosely based on the story, entitled Five Fingers, starring David Hedison and Luciana Paluzzi.