How to Kill a Judge (1974)
Perché si uccide un magistrato (internationally released as How to Kill a Judge, The Murder of a Magistrate and Why Does One Kill a Magistrate?) is a 1974 Italian crime-thriller film directed by Damiano Damiani. It is the final chapter in the Damiani's trilogy about mafia, after The Day of the Owl and Confessions of a Police Captain.
More at Wikipedia.