In the climax of the film, Robert Graysmith and Inspector David Toschi finally confront Arthur Leigh Allen as the prime suspect in the Zodiac killings.
Throughout the movie, Graysmith, a cartoonist at the San Francisco Chronicle, becomes obsessed with the Zodiac case and begins his own investigation into the identity of the elusive killer. Inspector Toschi, along with his partner Inspector William Armstrong, leads the official investigation into the Zodiac murders but struggles to solve the case.
In the final moments of the film, Graysmith gathers evidence pointing to Arthur Leigh Allen as the prime suspect. He confronts Allen at his workplace, but Allen denies any involvement in the killings. Graysmith is convinced of Allen’s guilt, but the evidence is circumstantial, and the case remains officially unsolved.
Following Allen’s death in 1992, Graysmith continues his investigation and writes a bestselling book about the Zodiac case. However, despite his efforts, the true identity of the Zodiac killer remains a mystery, and the case is never officially solved.
In the end, Graysmith’s obsession with the Zodiac case takes a toll on his personal life, and he is left haunted by the unsolved murders and the possibility that the killer may never be brought to justice.
Through its atmospheric climax and meticulous attention to detail, “Zodiac” offers a gripping portrayal of one of the most notorious unsolved mysteries in American history. As Graysmith and Toschi grapple with the elusive nature of the Zodiac killer, viewers are left with a sense of unease and fascination with the enigmatic figure who terrorized the San Francisco Bay Area in the late 1960s and early 1970s.