A woman was convicted on Wednesday of murdering one of France's richest men by shooting him four times while he was dressed in a latex suit and tied up in a chair during a sex game.

A 12-member jury at Geneva's Court of Assizes found former mistress Cecile Brossard guilty of killing her lover Edouard Stern four years ago. Brossard, 40, admitted killing the banker but said it was because he enraged her by suggesting she was a $1 million prostitute.

The jury accepted the prosecutor's assertion that it was murder, which is punishable by up to 20 years in prison. The sentence is expected Thursday.

The body of Stern, 50, was found in his penthouse apartment in Geneva in 2005. He was wearing a head-to-toe latex suit and had been shot twice in the head and twice in the body, authorities said.

Brossard was arrested two weeks later and confessed, according to Prosecutor Daniel Zappelli.

Before the jury withdrew to deliberate, the Frenchwoman stood up Wednesday to stress how sorry she was.

"I am not a thief. I am not poisonous," she told the court. "I am just desperately in love with a man and I will be forever."

She turned to Stern's former wife, Beatrice David-Weill, and his children and asked them to forgive her.

Brossard said Stern promised her $1 million to help her become financially independent and wanted to marry her.

Stern then deposited the sum in a special account for her, but the two quarreled over control of the money. Brossard denied that she killed him over the money, which she had sought only as proof of his love for her.

But the money and the promise of marriage went hand in hand, she said, adding that the love story was shattered when Stern blocked the bank account and she understood he would not marry her. She felt humiliated and used, she said.

During their last evening together, they had sex games with Stern wearing his latex suit and tied up on a chair in a submissive position, she recounted.

When he told her, "One million for a whore, that's expensive", she said she lost control.

That "made everything explode, my head, heart and mind," Brossard said. "Like a robot I went to get the gun in the drawer.

Brossard's lawyer Alec Reymond pleaded that it was a crime of passion, punishable by up to 10 years imprisonment.

But Prosecutor Zappelli said Brossard knew exactly what she was doing.

"Edouard Stern was not killed because of sex, although we talked a lot about it in this trial," he told the court Tuesday. "Neither was he killed out of love, but out of hate. In the end, the money was the reason for his death."

Brossard acted with cynical and calculated mind after the crime, removing incriminating evidence, flying to Australia and telling lies to her friends on the phone, prosecutors said.

Stern had a long background in investment banking, working for his family firm Banque Stern from the age of 22 and forcing his father out of the company two years later — with the help of two uncles.

Estimates of his wealth varied, but he was said to have been worth several hundred million dollars.

He sold the family business in 1985, but stayed on as chairman until 1998.

He also was once in line to succeed his father-in-law, Michel David-Weill, as head of the investment bank Lazard LLC, but left the company in 1997 after they argued.

He then moved to Geneva and set up his own investment fund, Investments Real Returns SA.