After a month of patient investigation, the problem remained unsolved. The poor devil of a Baudru could not be kept in prison indefinitely, and to place him on trial would be ridiculous. There was no charge against him. Consequently, he was released; but the chief of the Sûrété resolved to keep him under surveillance. This idea originated with Ganimard. From his point of view there was neither complicity nor chance. Baudru was an instrument upon which Arsène Lupin had played with his extraordinary skill. Baudru, when set at liberty, would lead them to Arsène Lupin or, at least, to some of his accomplices. The two inspectors, Folenfant and Dieuzy, were assigned to assist Ganimard.