L'impero (2001)

Dario Ferri, an investigator with the Rome anti-Mafia unit visits the dreaded Ma-fia killer Nicolo Panarea in prison. Dario has recently been the one to put him away and has been promoted to detective as a reward. He now hopes to put the cherry on his cake by actually getting Panarea to talk. Hardly is he left alone with Panarea in his cell, when the Mafioso draws a home-made knife and threatens to murder Dario if the prison staff get involved in any way. Then instead of taking Dario hostage and escaping Panarea cuts off his own little finger. This is to dem-onstrate that Dario will never succeed in getting him to break his 'Omerta', his oath of silence. Put to shame Dario leaves.