In 1970 Pasolini bought an old castle near Viterbo, several miles north of Rome, where he began to write his last novel, "Il Petrolio", where he denounced obscure dealing in the highest levels of government and the corporate world (Eni, CIA, the Mafia, etc.). The novel-documentary was left incomplete at his death. In 1972, Pasolini started to collaborate with the extreme-left association Lotta Continua, producing a documentary, "12 dicembre", concerning the Piazza Fontana bombing. The following year he began a collaboration for Italy's most renowned newspaper, "Il Corriere della Sera". At the beginning of 1975 Garzanti published a collection of his critical essays, "Scritti corsari" ("Corsair Writings").