American author Douglas Preston and Italian journalist Mario Spezi co-investigated the Monster of Florence case and published their findings in 2008. The investigation of the investigators took a dramatic turn: Spezi was arrested, and Preston was named as a suspect and effectively forced to leave Italy. The prosecutor responsible — Giuliano Mignini — later prosecuted an internationally famous separate case where critics identified identical patterns of prosecutorial conduct: elaborate narratives of satanic ritual and occult motive built on circumstantial inference. What was that subsequent high-profile case, and why does Mignini's conduct across both prosecutions serve as a specific example of a documented institutional failure in prosecutorial systems?