The film rights to Roderick Thorp’s 1966 novel, The Detective, were sold to independent producer and former actor Robert Evans, who intimated that he might himself “tackle the controversial role” of New York Police Department Detective Sergeant “Joe Leland,” the 1 Jun 1966 Var announced. Nearly five months later, however, the book’s option was picked up by producer Fred Kohlmar and director Mark Robson for Twentieth Century-Fox Film Corp., according to the 28 Oct 1966 DV.. Abby Mann was writing the screenplay, a starting date was set for the following summer, and Frank Sinatra was signed to play Leland. By the following year, the 22 May 1967 DV and 24 May 1967 Var broke the news that producer Aaron Rosenberg had taken over the project from Kohlmar, and Gordon Douglas would replace Robson as director if prior commitments could be rescheduled. Sinatra and Robson, who had previously worked together, reportedly did not see “eye-to-eye.” The Rosenberg-Douglas-Sinatra team had recently finished Twentieth Century-Fox’s private eye caper, Tony Rome (1967, see entry), with Sinatra in the title role, and were planning to shoot its sequel, The Lady in Cement (1968, see entry), as soon as they finished The Detective. By then, as noted in the 26 Apr 1967 Var, The Detective was a hot property because Roderick Thorp’s hardcover novel had sold 300,000 copies and Avon Books had just printed a first run of 800,000 paperbacks.
       Twentieth Century-Fox signed Frank Sinatra’s wife, Mia Farrow, to co-star with him and Lee Remick in The Detective as soon as she finished her role in Paramount Pictures’ Rosemary’s Baby (1968, see entry), which was set to begin shooting 21 Aug, according to the 15 Aug 1967 DV. Meanwhile, as reported in the 30 Aug 1967 Var, Rosenberg and Douglas were going to scout New York City locations in preparation for six weeks of filming there in Oct and Nov 1967, followed by four weeks of shooting interiors at Twentieth Century-Fox Studios in Los Angeles, CA. Abby Mann, known for writing socially conscious films such as Judgment at Nuremberg (1961, see entry), told the 29 Nov 1967 Var that as part of his deal, he would be on the set every day to revise or create new dialogue if needed. He added that his screenplay “differs sharply from the original novel.” Changing private eye Joe Leland to a police detective, Mann said, gave him “the opportunity to make several statements about the police and about society that were not in the novel.” Mann warned the 24 Sep 1967 LAT that the film had “shocking scenes in it, things that have never been seen in a film, things that have never been shown in a film before.”
       The 18 Oct 1967 Var announced that principal photography had begun two days earlier in New York City. That day’s NYT visited a location on East Sixty-Seventh Street, between Lexington and Third Avenue, where Joe Leland’s precinct headquarters were located in an old New York Police Department (NYPD) station house. In the scene, which required a dozen takes, Frank Sinatra escorted a “homosexual murderer” through a mob of reporters to a waiting car. “Of course, we’re just shooting little bits of dialogue at a time,” he told a real reporter. “It’d be different trying to do a big dramatic scene. You couldn’t do Hamlet [on the street].” The article indicated that Hollywood restaurateur “Prince” Mike Romanoff, who was in the crowd, was the film’s “assistant producer.” Aaron Rosenberg mentioned that the company would be in New York for six weeks, spending $1.4 million of the film’s $5.5-million budget there.
       Within a month, the 22 Nov 1967 Var reported that Rosenberg needed to shut down the picture at the end of the month until Mia Farrow finished Rosemary’s Baby. The 6 Nov 1967 LAT had already run an item on Sinatra losing his patience over his wife’s absence. The Detective was twelve days ahead of schedule, while director Roman Polanski’s Rosemary’s Baby was three weeks behind. Sinatra pressured his wife to “walk off the lot,” but she had no “stop date” in her Paramount contract and could legally be detained as long as necessary. Rosenberg had already finished shooting in New York and was currently completing all scenes without Farrow in Los Angeles. The news broke in the 23 Nov 1967 LAT that Frank Sinatra and Mia Farrow had agreed to “a trial separation.” A week later, the 30 Nov 1967 NYT announced Farrow’s replacement in The Detective by English actress Jacqueline Bisset. The 11 Dec 1967 DV announced that filming had ended the previous Friday, 8 Dec 1967, except for a day’s work by actor William Windom the following Monday.
       The Detective had its premiere in New York on 28 May 1968 and opened around the city the following day, according to a review in the 29 May 1968 NYT. Six weeks later, the 20 Jun 1968 LAT noted that The Detective would open in Hollywood, CA, on 26 Jun 1968. The NYT was unimpressed with Gordon Douglas’s “weak, unimaginative direction” and the film’s mix of “the real and the fake.” The 26 Jun 1968 LAT considered The Detective nothing more than a “tasteless” sequel to Tony Rome, the only difference being that it was filmed in New York instead of Miami, FL, with boxer Sugar Ray Robinson replacing boxer Rocky Graziano from the earlier movie. The 29 May 1968 Var mostly praised the film as being commercially “hot,” but criticized Abby Mann’s “sprawling, untidy, badly-structured” script, especially the twenty-four minutes of flashbacks in which Sinatra’s character relived his “unstable married life.”