The man could very well have been Nicolas Fouquet as he went missing after his arrest by Louis XIV. Fouquet was Minister of Finance for the King but had a number of detractors against him who told the king if he could build a chateau of this quality he must be stealing from the King. Apparently the King was jealous of the standing of Fouquet and the admiration of his new chateau so he was arrested and jailed never to be seen or heard of again. So was he behind the iron mask ? We will never know as there are no records of who it was or if it really happened but you never know.