It stars Jake Gyllenhaal, Mark Ruffalo, and Robert Downey Jr., with Anthony Edwards, Brian Cox, Elias Koteas, Donal Logue, John Carroll Lynch, Chloë Sevigny, Philip Baker Hall, and Dermot Mulroney in supporting roles.

One month later, the San Francisco Chronicle receives encrypted letters written by the killer calling himself "Zodiac", who threatens to kill a dozen people unless his coded message containing his identity is published.

Political cartoonist Robert Graysmith, who correctly guesses that his identity is not in the message, is not taken seriously by crime reporter Paul Avery or the editors and is excluded from the initial details about the killings.

Someone claiming to be Zodiac continues to send taunting letters and speaks on the phone with lawyer Melvin Belli on the KGO-TV morning talk show hosted by Jim Dunbar.

Graysmith learns that Allen lived close to Ferrin and probably knew her and that his birthday matches the one Zodiac gave when he spoke to one of Melvin Belli's maids.

[8] He pitched his adaptation of Zodiac to Mike Medavoy and Bradley J. Fischer from Phoenix Pictures, agreeing to write a spec script if he could have more creative control over it.

[12] For the young Fincher, he was drawn to the Zodiac story because he spent much of his childhood in San Anselmo in Marin County during the initial murders; he thought the killer "was the ultimate boogeyman".

Fincher, Fischer and Vanderbilt spent months interviewing witnesses, family members of suspects, retired and current investigators, the two surviving victims, and the mayors of San Francisco and Vallejo.

The filmmakers secured the cooperation of the Vallejo Police Department (one of the key investigators at the time) because they hoped that the film would inspire someone to come forward with information that might help solve the cold case.

[24] Michael Mann's Miami Vice, as well as his previous effort, Collateral (a co-production of Paramount and its then-sister studio DreamWorks, and which also starred Mark Ruffalo), were also shot with the camera but mixed in other formats.

[26] Fincher and Savides used the photographs of William Eggleston, Stephen Shore's work from the early Seventies, and actual photos from the Zodiac police files.

[26] The two men worked hard to capture the look and feel of the period as Fincher admitted, "I suppose there could have been more VW bugs but I think what we show is a pretty good representation of the time.

The filmmakers shot for five weeks in the San Francisco Bay Area and the rest of the time in Los Angeles, bringing the film in under budget, wrapping in February 2006.

"[12] Digital Domain handled most of the film's 200+ visual effects shots, including pools of blood and bloody fingerprints found at crime scenes.

Photographs of every possible angle of the area were shot with a high-resolution digital camera, allowing the effects crew to build computer-based geometric models of homes that were then textured with period facades.

[27] Several of the film's establishing shots of the 1970s-era Bay Area were created by the Marin County visual effects house Matte World Digital (MWD).

Fincher and music supervisor George Drakoulias searched for pop songs that reflected the era, including Three Dog Night's cover of "Easy to Be Hard".

Shire worked on it and incorporated textures of a Charles Ives piece called "The Unanswered Question" and Conversation-based cues, he found that he had 37 minutes of original music.

It was supposed to be released in time for Academy Award consideration but Paramount felt that the film ran too long and asked Fincher to make changes.

[17] To trim down the film to its official runtime, he had to cut a two-minute blackout montage of "hit songs signaling the passage of time from Joni Mitchell to Donna Summer."

[35] The director's cut of Zodiac was given a rare screening at the Walter Reade Theater in New York City on November 19, 2007, with Fincher being interviewed by film critic Kent Jones afterwards.

Disc 1 contains, in addition to a longer cut of the film, audio commentaries by Fincher and Gyllenhaal, Downey, Fischer, Vanderbilt, and author James Ellroy.

"[50] Nathan Lee in his review for The Village Voice wrote that director Fincher's "very lack of pretense, coupled with a determination to get the facts down with maximum economy and objectivity, gives Zodiac its hard, bright integrity.

"[51] Todd McCarthy's review in Variety magazine praised the film's "almost unerringly accurate evocation of the workaday San Francisco of 35–40 years ago.

"[52] David Ansen, in his review for Newsweek magazine, wrote, "Zodiac is meticulously crafted – Harris Savides's state-of-the-art digital cinematography has a richness indistinguishable from film – and it runs almost two hours and 40 minutes.

Ebert also praised the ensemble cast and, as a longtime columnist for The Chicago Sun-Times, asserted Zodiac was "intriguing in its accuracy" in showing the operation of a major newspaper.

"[57] Graham Fuller in Sight & Sound magazine wrote, "the tone is pleasingly flat and mundane, evoking the demoralising grind of police work in a pre-feminist, pre-technological era.

"[59] Andrew Sarris of The New York Observer felt that "Mr. Fincher's flair for casting is the major asset of his curiously attenuated return to the serial-killer genre.

"[61] David Thompson of The Guardian felt that in relation to the rest of Fincher's career, Zodiac was "the worst yet, a terrible disappointment in which an ingenious and deserving all-American serial killer nearly gets lost in the meandering treatment of cops and journalists obsessed with the case.

"[62] In France, Le Monde newspaper praised Fincher for having "obtained a maturity that impresses by his mastery of form", while Libération described the film as "a thriller of elegance magnificently photographed by the great Harry Savides."