Disgraced former IMF chief Dominique Strauss-Kahn’s legal woes deepened Monday as French prosecutors opened a preliminary probe into accusations he took part in a gang rape in the US. Prosecutors in Lille, where Strauss-Kahn and three others are charged in a vice case, said in a statement the probe centred on an incident “that could be described as gang rape” that took place in Washington, DC in December 2010. Strauss-Kahn, two businessmen and a police chief have been charged with “aggravated pimping in an organised gang” in Lille for allegedly organising a prostitution ring for orgies in France, the United States and elsewhere. Earlier this month prosecutors in the northern French city said investigating magistrates in the case had submitted new evidence, based on testimony from two Belgian sex workers, that could also implicate the men in a gang rape. Testimony from one of the prostitutes indicated that she had been forced into non-consensual sex acts while in Washington with Strauss-Kahn and the other accused. She has not filed a complaint. “I don’t see the coherence of opening preliminary investigations for gang rape when the person concerned, who was questioned at length, did not file a complaint for rape,” said one of Strauss-Kahn’s lawyers, Richard Malka. He said the opening of the probe “shows the incredible relentlessness” of investigators against his client.