A pizza cutter-toting lunatic posed as an FBI agent in a botched bid to spring Luigi Mangione out of his notorious Brooklyn jail, federal prosecutors said Thursday. Minnesota native Mark Anderson approached the intake area at the Metropolitan Detention Center and made the head-scratching claim that he had an order “signed by a judge” to free the accused cold-blooded killer, who is being held without bail, according to court records and law enforcement sources. When asked to show his credentials, Anderson allegedly took out a Minnesota driver’s license, and said that he had weapons in his bag.