Robert Graysmith (Jake Gyllenhaal) and Dave Toschi (Mark Ruffalo) are convinced that former suspect Arthur Leigh Allen is Zodiac. There are many facts that indicate that Allen is Zodiac: his Zodiac watch, the army boots, he knew Darlene (one of the first victims) and this was confirmed by Darlene's sister Linda, the guns he owned, during the time when he was in jail (for molesting a minor) the police stopped receiving letters from Zodiac; 48 hours after being questioned by Toschi, he moves to another residence; months after being released from jail, he sent a typewritten letter to Toschi saying "I'm sorry I'm not Zodiac. If you need my help, let me know" and the police received a new Zodiac letter; and some of the things written in the letters such as "Maybe I should shoot little kids" was confirmed by a friend of Allen and spelling mistakes were confirmed by Allen's brother and his wife. In the early 90s, Robert's book about Zodiac becomes a bestseller and one of police officer Mulanax's colleagues talks with Mike Mageau (the survivor of the attack seen at the beginning of the film) and Mageau identifies Allen as the one who shot him. Years later, before the police can question Allen, he dies of a heart attack. Paul Avery (Robert Downey Jr.) died in 2000. Four years later, the police close the Zodiac investigation. Toschi retired from the police force in the late 80s and was cleared of the charge that he supposedly sent a fake Zodiac letter to get attention. Robert Graysmith currently has a healthy relationship with his children.