Man in the Iron Mask Dumas also presented a review of the popular theories about the prisoner extant in his time in the chapter "L'homme au masque de fer" in the sixth volume of his non-fiction "Crimes Célèbres". The earliest surviving records of the masked prisoner are from late July 1669, when Louis XIV's minister, the Marquis de Louvois, sent a letter to Bénigne Dauvergne de Saint-Mars, governor of the prison of Pignerol, which at the time was part of France. In his letter, Louvois informed Saint-Mars that a prisoner named "Eustache Dauger" was due to arrive in the next month or so. Louvois instructed
Man in the Iron Mask suggested that Dauger may have poisoned Fouquet as part of a complex power struggle between Louvois and his rival Colbert. However, evidence has emerged that Dauger de Cavoye actually died in the Prison Saint-Lazare, an asylum run by monks which many families used in order to imprison their "black sheep". Documents have survived indicating that Dauger de Cavoye was held at Saint-Lazare in Paris at about the same time that Dauger, the man in the mask, was taken into custody in Pignerol, hundreds of miles away in the south. These include a letter sent to Dauger de Cavoye's sister, the