Initial reports suggested that the 80-year-old Coutinho's son Daniel, who suffers from mental illness, stabbed his father to death yesterday.
Police indicated that Coutinho's wife Maria das Dores Coutinho, 62, was in serious condition and recovering in hospital from stab wounds to the chest and liver.
Among Coutinho's best known work was his 1967 drama "ABC do Amor" (The ABC of Love), which he directed with Argentina's Rodolfo Kuhn.
It competed in the 17th Berlin International Film Festival, where it was nominated for a Golden Bear.
Sao Paulo-born Eduardo Coutinho was widely considered one of Brazil's finest directors.
Breaking off law studies at 21, he swiftly found his place in film and theater. Coutinho moved to France, where he produced his first documentaries in the late 1950s and honed his art at the Institute for Advanced Cinematographic Studies (IDHEC).
Another landmark work was "Twenty Years Later" -- a docudrama about an executed peasant leader that took 20 years to come to fruition after a 1964 military coup forced Coutinho to break off filming in Brazil.
Coutinho's "Edificio Master," an intimate portrait of families living in an apartment block in Rio's Copacabana, earned him a series of awards, including the Gramado Film Festival's prestigious Golden Kikito in 2002.
Last year, he was inducted into the US Academy of Motion Picture Arts and Sciences.
Last year, Coutinho indicated he planned to make a documentary about popular protests that took place across Brazil in June against corruption, mismanagement and costs associated with staging the World Cup and the 2016 Rio Olympics.
