THE pivotal character in a French prostitution ring that landed former International Monetary Fund (IMF) chief Dominique Strauss-Kahn in court for “pimping” was the first to take the stand in the trial on Tuesday.

Rene Kojfer, 74, former public relations manager for the luxury Carlton Hotel in the northern city of Lille, is accused of running a high-end prostitution ring that organised sex parties for local businessmen and police officials, often in his hotel.

It was during a probe into the so-called “Carlton Affair” that investigators stumbled across the alleged involvement of Strauss-Kahn, whose high-flying career and presidential prospects imploded when a New York hotel maid accused him of sexual assault in 2011.

Kojfer is accused of procuring prostitutes for members of Strauss-Kahn’s entourage — also among the 14 accused — who threw sex parties for the then-IMF chief in Paris, Brussels and Washington.

Strauss-Kahn said Monday he had never set foot in the Carlton and did not know Kojfer and notorious Belgian brothel-owner Dominique Alderweireld, known as “Dodo the Pimp”, who employed the prostitutes that attended the sex parties with him.

While his is only a small part in the multi-faceted trial, the disgraced 65-year-old former finance minister — known in France as DSK — is the star attraction at the austere courthouse in Lille. However he will not be in court again until he takes the stand himself next week.

Before then, Kojfer, Alderweireld and some of the prostitutes who took part in the debauched parties are likely to be questioned about their links to DSK’s entourage, and his presence at the sex parties.

Bernard Lemaire, the chief of the four judges who will oversee the three-week, jury-less trial, read out the charges against Kojfer of organising and benefiting from the prostitution of eight women, some of whom attended the DSK orgies.

Kojfer denies the charge of “aggravated pimping”, saying he was merely doing a service for his friends by introducing them to the prostitutes he knew.

His lawyer, Hubert Delarue, sought to portray Kojfer as a man who revelled in having friends in high places, but who was naive, suffered from alcoholism and was given to telling tall tales about his ties to powerful people. Kojfer agreed with this, even revealing he had been beaten by his ex-wife.

Delarue is laying the ground to defend prosecution claims that Kojfer boasted in intercepted calls of providing prostitutes for DSK.

“Do you really want us to believe that all these people would be friends with a simple fellow, a naive person? That you had nothing else to offer?” asked prosecutor Aline Clerot.

Lurid details of group sex and high-end prostitution are likely to emerge in the trial, which has Strauss-Kahn sharing the dock with a colourful cast of characters including luxury hotel managers, a prostitute, police, as well as “Dodo the Pimp.”

Lemaire said “the court is not the guardian of morals but of the law and its proper application.”

Strauss-Kahn admits to being a “libertine” who took part in orgies, but denies knowing that the women at the parties were prostitutes.

“In these circumstances one isn’t always clothed, and I challenge you to tell the difference between a prostitute naked and any other woman naked,” Strauss-Kahn’s lawyer Henri Leclerc, 84, said in 2011.

The economist nonetheless finds himself facing 10 years in prison and a fine of up to 1.5 million euros ($1.7 million) for “aggravated pimping in an organised group”, with investigating judges believing he played a role in initiating the sex parties and organising the presence of the prostitutes.

Prostitution is legal in France but procuring — the legal term for pimping which includes encouraging, benefiting from or organising prostitution — is a crime.

The trial is the latest in a series of cases offering a peek behind the bedroom door of a man once tipped as a potential challenger to former French president Nicolas Sarkozy.

France was stunned when it saw Strauss-Kahn paraded handcuffed in front of the world’s cameras after a New York hotel maid accused him of sexual assault in May 2011 — a case that was eventually settled in a civil suit.