Diwana (1967)

Meet Pyarelal, a simple-minded, naive young man, orphaned at birth, living with a Muslim landlady, Fatima, who treats him like her son. When the police arrest Pyarelal on the charge of murder, no one really believes that this harmless man could harm anyone, leave alone kill. Their belief is shattered when Pyarelal openly admits in Court that he has indeed committed this crime, and demands capital punishment for it.