This chain of events brought suspicion toward Apollinaire. He had known Pieret. He had been in contact with Picasso. The investigators looking for anyone who might have had access to stolen museum property, or connections to those who did, found Apollinaire’s name appearing too many times for comfort.
On September 7, 1911 — more than two weeks after the theft — two detectives arrived at Apollinaire’s Paris apartment with a warrant. He was taken to the Palais de Justice and then to La Santé prison. The official charge was “complicity in theft.” His registration in prison records used his birth surname, Kostrowitsky — a name that underscored how thoroughly his public identity had been constructed around a pen name rather than his Polish-Russian family origins.
Apollinaire, by all accounts, was deeply shaken by the arrest and imprisonment. He wrote poetry in his cell. His friends organized a committee for his release. His brother attempted to visit. His lawyer intervened with the examining magistrate. After approximately five days in La Santé, he was released on provisional liberty on September 12, 1911.
Picasso was separately questioned. He denied everything, including, in one mortifying moment before an examining magistrate, that he even knew Apollinaire — a denial he later acknowledged had been driven entirely by fear. He was not charged.
The examining judge, Henri Drioux, found the testimony of both men — however emotionally anguished — convincing on the central question. Neither Apollinaire nor Picasso had anything to do with the theft of the Mona Lisa. The case against them was dropped with a warning about the earlier statuette transactions. Apollinaire published an account of his detention in *Paris* on September 14, 1911.