Silent Fall

Silent Fall is a 1994 mystery film about a boy with autism who is the only witness to a savage double murder. The film was directed by Bruce Beresford and stars Richard Dreyfuss, Linda Hamilton, John Lithgow, J. T. Walsh and Liv Tyler.

The psychological drama is provided by the fact that not even Jake can entice Tim to communicate what he has or has not seen regarding the crime. Tims sister, Sylvie, is protective of him. She eventually warms to Jakes efforts, but is concerned when she learns he was implicated in the suicide of another young child who was under his care.Jake gradually befriends Tim. At first, Jake thinks that Tim is trying to communicate by cutting up playing cards, but Sylvie reveals that Tim is good at mimicking voices. Jake is able to trigger Tims memory so that Tim mimics the voices he heard on the night of the murder by using the trigger phrase God Damn, which were the first words Tim heard from the murder. He attempts to piece together the chronology of the murder, suspecting that Tim interrupted a fight between his parents and an intruder. ........

Source: Wikipedia