I Knew It Was You: Rediscovering John Cazale is a 2009 American documentary film about actor John Cazale, directed by Richard Shepard and produced by Brett Ratner, Stacey Reiss and Richard Shepard. The film received its title from a famed line from The Godfather Part II directed toward Cazale's character of Fredo Corleone, and acts as a retrospective of Cazale's distinguished acting career, which was cut short at age 42 when he died of lung cancer. The film was produced with the cooperation of Meryl Streep, who was living with Cazale at the time of his death. It features interviews with a number of his notable co-stars and directors.