DSK, as his is known in France, was released after being in detention for 32 hours in the northern French city of Lille on Wednesday.
But he will be summoned to answer charges of complicity with an organised vice ring, which can lead up to 20 years in jail, and of profiting from embezzled company fund.
Strauss-Kahn denies knowing that women involved in sex parties he took part in were prostitutes, his lawyer having argued that it is impossible to “tell the difference between a nude prostitute and a well-off woman nude”.
But one of the women involved has said that he asked her for her mobile phone number and how much she charged.
The scandal, known as the “Carlton affair” after the hotel in Lille which is a well-known meeting place for the business and political elite of the Socialist-run city, blew up after New York prosecutors dropped charges against Strauss-Kahn in the Diallo case.
Eight people are facing trial in connection with it.
They include three executives from the hotel, a well-known lawyer and police commissioner Jean-Christophe Lagarde.
During his latest detention, Strauss-Kahn was also questioned by the French police international inquiries department, the IGPN, in connection with their investigation into Lagarde.
It is not yet known whether Strauss-Kahn will travel to New York to appear in the civil case there but the Carlton affair is likely to be cited by Diallo’s lawyers, as is the accusation of rape made by journalist Tristane Banon.
Supporters of François Hollande claimed that President Nicolas Sarkozy’s campaign to be reelected will be the “dirtiest campaign seen in France for 30 years” after a top official of Sarkozy’s UMP accused the Socialist presidential candidate of hushing up the Strauss-Kahn affair and other scandals that have hit party members.
Hollande, who was Socialist Party national secretary for 11 years, “must have known about” “cash and sex scandals”, including the Strauss-Kahn affair and corruption scandals concerning Senator Jean-Noël Guérini from Marseille and the Calais regional party, UMP National Secretary Sébastien Huyghe declared on Tuesday.
He demanded that Hollande “explain himself”.
Hollande’s campaign organiser, Pierre Moscovici, on Wednesday hit back, declaring the statement “so low, so wrong, so ridiculous that it doesn’t deserve a reply”.
Nevertheless, he went on to blame Sarkozy personally for the attack.
“This is no ordinary campaign,” Moscovici told BFM-TV. “Nicolas Sarkozy is preparing dirtiest campaign seen in France for 30 years.”