Jean-Christophe Lagarde has been arrested on suspicion of pimping, Radio France Internationale reported Friday. Several businessmen are also under investigation, officials said.
Strauss-Kahn was arrested on a plane at Kennedy International Airport in May on charges of sexually assaulting a New York hotel housekeeper. Those charges were later dropped.
Le Figaro reported that David Roquet, an executive with the French construction company Eiffage, helped pay for sex parties at a Paris hotel attended by both Lagarde and Strauss-Kahn. Roquet was arrested Oct. 14.
Lagarde also allegedly traveled to Washington on trips paid for by businessmen. Le Figaro said the last trip was just before Strauss-Kahn's New York arrest.
Lille, an industrial city in northern France, is the center of the country's fourth-largest metropolitan area.