On 12 December 1969 a bomb exploded at the Piazza Fontana in Milan . Among those brought in for questioning was militant anarchist Giuseppe Pinelli . On 15 December 1969 , while in police custody Pinelli fell from a fourth floor window of the police building in Milan . The policemen present in the interrogation room claimed that Pinelli committed suicide , but many leftist circles believed him to have been murdered . An initial investigation in 1970 ruled Pinelli 's death an accident . ( A subsequent inquiry in 1975 concurred , holding that Pinelli had fainted due to an " active illness " )
Piazza Fontana
Piazza Fontana bombing
Adriano Sofri