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").