French prosecutors Tuesday dropped a probe into whether former IMF chief Dominique Strauss-Kahn took part in a gang rape in the United States, but kept open another one into alleged pimping.
Strauss-Kahn had denied any criminal wrongdoing in the incidents investigated, which involved evenings with prostitutes and took place in Washington in late 2010 while he was still International Monetary Fund boss.
The Belgian woman who was allegedly raped wrote to French police in August to say she had consented to sex acts and was not pressing any charges, the prosecutor's office in Lille said.
It added in a statement that as no offence had been committed, a preliminary investigation was being shelved.
Strauss-Kahn, two businessmen and a police chief were charged in March with "aggravated pimping in an organised gang" for allegedly contributing to the procurement of prostitutes for sex parties.
The former Socialist politician admits attending orgies in France and the United States but claims he did not know the women involved were being paid to take part.
The pimping investigation is ongoing with another hearing due at the end of November but Strauss-Kahn's lawyer, Henri Leclerc, said he was confident his client would ultimately be cleared of any wrongdoing.
"There is no hint he was involved in pimping. You will see that emerge although right now this is fuelling scandal."
Strauss-Kahn's career collapsed spectacularly after his arrest last year on accusations he sexually assaulted a New York hotel maid.
Criminal charges against him were quickly dropped because of doubts over the reliability of the alleged victim's testimony.
She is however pursuing a civil case against her alleged attacker while Strauss-Kahn has filed a counter suit against her for defamation and is pursuing a claim of malicious prosecution through the American courts.
Strauss-Kahn's high-profile arrest and the public airing of the lurid details of the allegations made against him effectively destroyed his ambitions of becoming the Socialist candidate for France's presidential elections in May and June.
His reputation was further shredded on his return to France as details of another alleged attack and the pimping case surfaced.
The case, known as the "Carlton affair" in France, centres around allegations that business leaders and police officials in Lille operated a vice ring supplying girls for sex parties, some of which are said to have taken place at the Carlton Hotel in the northern city.
Among Strauss-Kahn's fellow accused is Jean-Christophe Lagarde, a police commissioner, and Rene Kojfer, the former public relations officer at the Carlton.
Lawyers for Lagarde and Kojfer have claimed their clients have effectively been caught up in a political witch-hunt against Strauss-Kahn, arguing that there would have been no probe but for his involvement.
Strauss-Kahn's wife of some two decades, Anne Sinclair, loyally stood by him when the New York scandal erupted but the couple have since split.