Zodiac Ending Explained: The Chilling and Unresolved Mystery Behind Fincher’s Serial Killer Thriller

David Fincher’s Zodiac is one of the most notable films of the past two decades, blending the journalistic investigation with a serial killer thriller. It is based on the true events surrounding the infamous Zodiac Killer, a mysterious figure responsible for a series of murders in Northern California during the late 1960s and early 1970s.

Despite extensive efforts by the police and journalists to uncover the killer’s identity, the case remains unsolved. The film explores the unresolved mystery, presenting a theory about the killer’s identity but leaving room for viewers to form their own conclusions.

The Zodiac Killer first made his presence known on August 1, 1969, when he sent cryptic letters to three California newspapers: the Vallejo Times Herald, the San Francisco Chronicle, and the San Francisco Examiner. These letters took credit for a pair of murders at Lake Herman Road and Blue Rock Springs. In these attacks, the killer ambushed two couples, killing one of each pair and injuring the other.

The Zodiac also sent a 408-symbol cryptogram that taunted authorities, and eventually, it was solved by a married couple in Salinas, revealing disturbing messages about the killer’s enjoyment of murder. In his next letter, the killer introduced himself as the Zodiac, claiming responsibility for 37 murders, though the true number is widely believed to be seven.

Police Investigation and Failures

The police were under immense pressure to identify and catch the Zodiac, but the investigation faced several challenges. The murders took place across different jurisdictions, making coordination among law enforcement agencies difficult. With limited evidence and no consistent leads, the Zodiac remained elusive.

Over time, several suspects were considered, but none of them were definitively linked to the crimes. Ultimately, the Zodiac Killer was never caught, and the case remains one of the most frustrating unsolved mysteries in American criminal history.

In 2007, David Fincher brought the Zodiac case to the big screen with his film Zodiac. Written by James Vanderbilt, the film spans several years and focuses on multiple characters trying to crack the case. Among them are journalist Paul Avery (Robert Downey Jr.), cartoonist Robert Graysmith (Jake Gyllenhaal), and San Francisco police inspector Dave Toschi (Mark Ruffalo).

Although the film shifts perspectives, Graysmith becomes the central character, with the story largely drawn from his books. Unlike Fincher’s earlier work, Seven, which centered on graphic violence, Zodiac is more focused on obsession and its impact on those involved in the case.

The Quest for the Zodiac Killer’s Identity

Throughout the film, multiple suspects are presented, but Graysmith becomes fixated on Arthur Leigh Allen, played by John Carroll Lynch. The circumstantial evidence against Allen is compelling, but there is no conclusive proof linking him to the murders. The film highlights Graysmith’s obsession with Allen, as he becomes increasingly determined to confront the suspect.

The tension builds as Graysmith, in 1983, finally tracks Allen down at a hardware store. They exchange a silent, tense gaze, with Graysmith convinced that Allen is the Zodiac, but the film leaves the question open.

The film’s ending is both chilling and anticlimactic. In a final epilogue, one of the Zodiac’s surviving victims identifies Allen from a lineup of mugshots, but before authorities can question him further, Allen dies of kidney failure. While the film suggests that Allen could have been the killer, it acknowledges that the evidence remains circumstantial.

Additionally, later DNA testing on a Zodiac letter ruled out Allen as the source of certain DNA found on it, though Graysmith himself disputes this result. In the end, Fincher’s film mirrors the reality of the case: the Zodiac Killer’s true identity may never be known, leaving room for continued speculation and mystery.