Former IMF director Dominique Strauss-Kahn arrived at a police station in northern France on Tuesday to face questioning as part of a probe into a prositution ring.
Strauss-Kahn arrived at the Gendarmerie barracks in the city of Lille shortly before 9:00am (0800 GMT), for what could be up to 48 hours of interrogation over what has become known as the "Carlton scandal".
French investigators suspect that a circle of senior northern business executives based in Lille, in collusion with senior police officers, ran a network supplying escorts to sex parties in several countries.
Several well-known local figures have been charged with pimping and misuse of company funds, and Strauss-Kahn faces allegations that he knowingly took part in orgies paid for by firms involved in public contracts.
The 62-year-old former Socialist minister admits that he had an adventurous sex life, but denies any suggestion that he knew the women at the parties were paid or that the bill had been picked up by the companies.
He was brought into the police station in a car with tinted windows, but his face was visible and a gendarmerie spokesman confirmed that the suspect was the former head of the International Monetary Fund.