Fact1: San Francisco Chronicle receives encrypted letters written by killer, Fact2: Political cartoonist Robert Graysmith is excluded from initial details about killings, Fact3: Avery At makes fun of Graysmith bar, Fact4: San Francisco police detectives and partner Bill Armstrong are assigned to case, Fact5: Someone claiming to be Zodiac continues to send taunting letters on television talk show
Output: On July 4, 1969, an unknown man attacks Darlene Ferrin and Mike Mageau with a handgun at a lovers lane in Vallejo, California. Mageau survives. One month later, the San Francisco Chronicle receives encrypted letters written by the killer calling himself the Zodiac and taunting the police. Political cartoonist Robert Graysmith is not taken seriously by crime reporter Paul Avery or the editors and is excluded from the initial details about the killings. When the newspaper publishes the letters, a married couple deciphers one. In September, the killer attacks law student Bryan Hartnell and Cecelia Shepard at Lake Berryessa in Napa County; Shepard dies two days later. At a bar, Avery makes fun of Graysmith before they discuss the coded letters. Graysmith interprets the letter, which Avery finds helpful, and Avery begins sharing information. One of Graysmiths insights about the letters is that the Zodiacs reference to man as the most dangerous animal of them all is a reference to the film The Most Dangerous Game, which features General Zaroff as a man who hunts live human prey. Two weeks later, San Francisco taxicab driver Paul Stine is shot and killed in the citys Presidio Heights district. The Zodiac killer mails pieces of Stines bloodstained shirt to the Chronicle along with a taunting letter. San Francisco police detectives Dave Toschi and his partner Bill Armstrong are assigned to the case, and work closely with Vallejos Jack Mulanax and Captain Ken Narlow in Napa. Someone claiming to be Zodiac continues to send taunting letters and speaks on the phone with lawyer Melvin Belli on a television talk show. In 1971, Detectives Toschi, Armstrong, and Mulanax question Arthur Leigh Allen, a suspect in the Vallejo case. They notice that he wears a Zodiac wristwatch, with the same logo used by the killer. However, a handwriting expert insists that Allen did not write the Zodiac letters, even though Allen is said to be ambidextrous. Avery receives a letter threatening his life; becoming paranoid, he turns to drugs and alcohol. He shares information with the Riverside Police Department, angering Toschi and Armstrong. The cases notoriety weighs on Toschi, who is unable to sit through a Hollywood film, Dirty Harry, loosely based on the Zodiac case. In 1978, Avery moves to the Sacramento Bee. Graysmith persistently contacts Toschi about the Zodiac murders, and eventually impresses him with his knowledge of the case. While Toschi cannot directly give Graysmith access to the evidence, he provides names in other police departments where Zodiac murders occurred. Armstrong transfers from the San Francisco Police homicide division and Toschi is demoted for supposedly forging a Zodiac letter. Graysmith continues his own investigation, profiled in the Chronicle, and gives a television interview about the book he is writing about the case. He begins receiving phone calls with heavy breathing. As his obsession deepens, Graysmith loses his job and his wife Melanie leaves him, taking their children. Graysmith learns that Leigh lived close to Ferrin and probably knew her, and that his birthday matches the one Zodiac gave when he spoke to one of Bellis maids. While circumstantial evidence seems to indicate his guilt, the physical evidence, such as fingerprints and handwriting samples, dont implicate him. In December 1983, Graysmith tracks Allen to a Vallejo Ace Hardware store, where he is employed as a sales clerk; Graysmith stares at him. Eight years later, after Graysmiths book Zodiac has become a bestseller, Mageau identifies Allen from a police mugshot.