GENEVA - A French woman pleaded guilty on Wednesday to killing a French banking scion after kinky sex and an argument over $1 million, saying it was a crime of passion.

Cecile Brossard, an artist who is now 40, sat impassively of the Geneva courtroom, her blonde hair pulled back in a bun, with the family of her late lover Edouard Stern seated just a meter behind her.

The defense will plead it was a crime of passion, Brossard's defense lawyer Alec Reymond told the courtroom.

The 50-year-old Stern -- the 38th richest man in France, whose friends included President Nicolas Sarkozy and Socialist politician Laurent Fabius -- was shot dead in his penthouse apartment in the Swiss city on February 28, 2005.

The killing of Stern, a banker known for his abrasive style who ran an investment fund out of Geneva and lent advice on some of Europe's largest mergers, rocked Geneva banking circles.

His body, with four bullet holes, was found clad from head-to-toe in a flesh-colored latex suit, which police say was linked to sado-masochistic sex.

Brossard confessed to killing Stern with his own pistol after an argument over $1 million Stern put into her Swiss account after she demanded it saying it would be proof of his love for her and then blocked it after she refused to return it.

A jury of 12 -- seven men and five women -- with three alternates was chosen to hear the case.

The judge accepted a request by the Stern family for the testimony by two of his three young adult children, Mathilde and Louis, to be heard immediately behind closed doors. A third, Henri, was excused from testifying because of exams.

Given their sadness and youth, we request a private hearing, said Marc Bonnant, who represents Stern's three children in the case.

Stern's ex wife, Beatrice Stern, sat next to her children until being asked to leave by the judge as she was not among the civil party bringing the case against Brossard.

The Stern family requested that a video reconstituting the crime also be shown behind closed doors, saying they feared piracy of the images.

But the judge refused, saying: I expect the public to respect the strict ban on taking photos.

Defense lawyers Reymond and Pascal Maurer won a motion for the court to hear phone messages left by Stern on Brossard's telephone which they say will show his years of cruelty to Brossard, whom he met in 2001.

Geneva chief prosecutor Daniel Zappelli agreed, telling the court: It is useful for the jury to hear the voice of the deceased.

The family has said it will seek a conviction for murder, which carries a maximum 20-year prison term, as opposed to a crime of passion, a 10-year maximum. A verdict is expected on June 19.

(Editing by Jon Boyle)