I give this movie a 3.5 out of 5.
Starring Jake Gyllenhaal (1980-) of Los Angeles, California, USA (Nightcrawler {2014} as Louis Bloom, Brokeback Mountain {2005} as Jack Twist, Prisoners {2013} as Detective Loki, Donnie Darko {2001} as Donnie Darko) as Robert Graysmith, Mark Ruffalo (1967-) of Kenosha, Wisconsin, USA (The Kids Are All Right {2010} as Paul, Spotlight {2015} as Mike Rezendes, The Avangers movies {2012, 2015, 2018, 2019} as Bruce Banner/The Hulk, Foxcatcher {2014} as David Schultz) as Inspector David Toschi, Anthony Edwards (1962-) of Santa Barbara, California, CA (ER {1994-2008} as Mark Greene, Top Gun {1986} as Goose, Revenge of the Nerds {1984} as Gilbert, Flipped {2010} as Steven Loski) as Inspector William Armstrong, Robert Downey Jr. (1965-) of Manhattan, New York City, New York, USA (Iron Man movies {2008, 2010, 2013} as Tony Stark, Avengers movies {2012, 2015, 2018, 2019} as Tony Stark/Iron Man, Chef {2014} as Marvin, The Soloist {2009} as Steve Lopez) as Paul Avery, Brian Cox (1946-) of Dundee, Scotland, UK (X2: X-Men United {2003} as William Stryker, Troy {2004} as Agamemnon, Adaptation. {2002} as Robert McKee, Super Troopers {2001} as Captain O'Hagan) as Melvin Belli, John Carroll Lynch (1963-) of Boulder, Colorado, USA (The Founder {2016} as Mac McDonald, Fargo {1996} as Norm Gunderson, Gothika {2003} as Sheriff Ryan, White Orchid {2018} as Sheriff Mann) as Arthur Leigh Allen, Richmond Arquette (1963-) of New York City, New York, USA (The Curious Case of Benjamin Button {2008} as John Grimm, Broken Blood {2013} as Peebo, Halloween {2007} as Deputy Charles, Smashed {2012} as Arlo) as Zodiac 1/Zodiac 2, Bob Stephenson (1967-) of Oxnard, California, USA (Fight Club {1999} as Airport Security Officer, Lady Bird {2017} as Father Walther, Our Idiot Brother {2011} as Officer Washburn, Jericho {2006-2008} as Jimmy) as Zodiac 3, John Lacy (1965-) of Iowa City, Iowa, USA (Just Mercy {2019} as Bill Freeman, Office Manager; American Crime Story {2018} as Howard Madson, Hell on Wheels {2014} as Virgil Farnsworth, Sons of Anarchy {2014} as Ken Haas) as Zodiac 4, Chloe Sevigny (1974-) of Springfield, Massachusetts, USA (Boys Don't Cry {1999} as Lana Tisdel, Big Love {2006-2001} as Nicolette Grant, Love & Friendship {2016} as Alicia Johnson, Slow Mcahine {2020} as Chloe) as Melanie, Ed Setrakian (1928-) of Adkin, West Virginia, USA (Three Days of the Condor {1975} as Customer, Peron of Interest {2012} as Grifoni, The Hard Way {1991} as Chief Villain, Blue Collar Boys {2013} as Gene) as Al Hyman, John Getz (1946-) of Davenport, Iowa, USA (The Social Network {2010} as Sy, Blood Simple {1984} as Ray, The Fly {1986} as Stathis Boranos, Brampton's Own {2018} as Bart) as Templeton Peck, John Terry (1950-) of Florida, USA (The Living Daylights {1987} as Felix Leiter, Full Metal Jacket {1987} as Lt. Lockhart, Of Mice and Men {1992} as Slim, Nine Dead {2010} as Shooter) as Charles Thieriot, Candy Clark (Norman, Oklahoma, USA (American Graffiti {1973} as Debbie, The Man Who Fell to Earth {1976} as Mary-Lou, Blue Thunder {1983} as Kate, Two Girls {2018} as Ida as an Adult (voice) as Carol Fisher and Elias Koteas (1961-) of Montreal, Quebec, Canada (The Thin Red Line {1998} as Capt. Staros, The Prophecy {1995} as Thomas Dagget, Shooter {2007} as Jack Payne, Crash {1996} as Vaughan) as Sgt. Jack Mulanax.