The probe comes just as New York prosecutors are weighing whether or not to go ahead with a case in which a chambermaid accused Strauss-Kahn — long considered a top contender for France's presidency — of sexual assault. Questions have surfaced about the maid's credibility, throwing the high-profile case into disarray.
Back in France, novelist and journalist Tristane Banon filed a criminal complaint this week saying that Strauss-Kahn attacked her in an empty apartment in 2003 during an interview for a book project, struggling with her on the floor as he tried to tear off her clothes.
An official in the Paris prosecutor's office said Friday that a preliminary investigation has been opened into the complaint. The official was not authorized to be publicly named because the investigation is under way.
The probe allows investigators from a special police brigade to question Banon and those close to her about the eight-year-old incident.
It could also allow French investigators to question Strauss-Kahn, though most likely not unless and until he returns to France. New York authorities have kept his passport pending a decision on what happens in the case there.
Strauss-Kahn quit as head of the International Monetary Fund after he was arrested in New York in May based on accusations of assault made by a hotel maid. Strauss-Kahn denies wrongdoing, and last week, he was released without bail after prosecutors said publicly that the maid has a history of lying.
Questions have also surfaced about the viability of the French accusation against Strauss-Kahn.
Banon made no official report of being victimized after the alleged attack, and Banon's lawyer has not described any physical evidence that could be brought against Strauss-Kahn.
Banon has acknowledged the difficulty of proving her case, saying she took action to deal with the trauma of the alleged incident and to refute those who say she's been lying.
She said in an interview with the magazine L'Express that Strauss-Kahn grabbed her hand and arm before the two fell to the floor of his apartment and fought for several minutes.
Strauss-Kahn's lawyers have called the incident "imaginary" and threatened to file a criminal complaint accusing Banon of slander.
After the preliminary probe into her claim, which could take weeks or months, the Paris prosecutor's office could decide to drop the case or pursue the investigation, which could eventually lead to a trial.
The probe will help prosecutors determine whether her allegations support a charge of attempted rape, rather than the less serious crime of sexual assault. Under French law, sexual assault is an attack that does not involve an attempt to penetrate the victim. It has a three-year statute of limitations — meaning the 2003 incident would be to old to prosecute — compared with 10 for attempted rape.