French politician Andre Bettencourt and his wife Liliane Bettencourt at the castle of Versailles in 1973. (AFP via Getty Images)

Liliane Bettencourt, a French heiress to the L’Oréal cosmetics fortune who became embroiled in a family feud that exploded into a financial and political scandal involving former French president Nicolas Sarkozy, died Sept. 20 at her home near Paris. She was 94.

Her daughter, Françoise Bettencourt-Meyers, announced her death but did not disclose the cause. Mrs. Bettencourt had been reported to have dementia and Alzheimer’s disease and had been under the guardianship of her family since 2011.

In recent years, Forbes magazine had ranked Mrs. Bettencourt as the richest woman in the world, with an estimated net worth of about $45 billion. As of 2015, she had a 33 percent stake in L’Oréal, the world’s largest cosmetics firm.

The only child of French chemist Eugène Schueller, Mrs. Bettencourt began working at her father’s Paris-based beauty and hair-care company as an apprentice at 15 and modeled for the firm’s early labels. She inherited the company after her father’s death in 1957 and retained a controlling stake in L’Oréal after it went public on the Paris stock exchange in 1963.

Alongside L'Oréal chief François Dalle, she expanded the firm's reach, adding cosmetics and fragrance lines and acquiring other beauty businesses, including Lancôme, Kiehl's, Maybelline and Garnier.

Mrs. Bettencourt in Paris in 1988 (Gerard Fouet/AFP via Getty Images)

Other than being photographed for luxury magazines and society pages, Mrs. Bettencourt remained largely out of the media limelight until details about her troubled relationship with her daughter, Bettencourt-Meyers, became public.

In 2007, her daughter sued François-Marie Banier, a celebrity photographer and playboy 25 years Mrs. Bettencourt’s junior, for allegedly exploiting her mother’s mental frailty to obtain gifts totaling more than $1 billion, including cash payments, Picasso and Matisse paintings and a private island in the Seychelles.

Bettencourt-Meyers decided to take legal action against Banier after her mother made him the sole heir to her fortune. She blamed Mr. Banier for the strained relationship between mother and daughter.

“The strategy of Mr. Banier was not just to divide and conquer. It was to break and conquer,” she said in court testimony. “It was programmed destruction.”

By most accounts, the friendship between Banier and Mrs. Bettencourt began in 1987, after he took photos of her for the French photo magazine Egoïste. He said his companionship motivated Mrs. Bettencourt’s largesse.

“Liliane wanted to do things for me, to ease my life,” he said in court. “I refused things like a mansion. But she took it so poorly. It’s really hard to cross that extraordinary woman.”

Dubbed the “Bettencourt Affair,” the soap-opera-like court proceedings made headlines for years. For some time, the L’Oréal matriarch and her daughter communicated exclusively through frosty television and newspaper interviews, which added to the tabloid fodder.

“I can’t understand what fly bit my daughter,” Mrs. Bettencourt told the French weekly Le Journal du Dimanche in 2008. “Maybe jealousy. My daughter is rather introverted, and someone who puts himself out there like François-Marie Banier, well, it might be very annoying.”

The family feud became a full-blown legal and political drama in June 2010, when a series of secret tapes, recorded by Mrs. Bettencourt’s former butler, were passed to the police and later leaked to the French investigative website Mediapart.

The recordings, made between May 2009 and May 2010, captured members of Mrs. Bettencourt’s staff exploiting her for personal gain and discussing tax avoidance, secret Swiss bank accounts and — most explosively — illegal campaign donations.

In the weeks following the tapes’ release, a former accountant to Mrs. Bettencourt claimed that her job entailed handing out cash-stuffed envelopes to conservative politicians. She said that Éric Woerth, Sarkozy’s former budget minister, had accepted donations amounting to 150,000 euros from Mrs. Bettencourt for Sarkozy’s 2007 presidential campaign, far exceeding the 4,600 euro legal limit on individual campaign contributions.

The accountant also claimed that Sarkozy sought and accepted regular cash envelopes from Mrs. Bettencourt’s office while he was mayor of Neuilly.

Sarkozy denied the allegations, but his approval ratings tumbled amid several other inquiries into his election to the presidency in 2007. Public scrutiny heightened when it was revealed that Mrs. Bettencourt had received a tax rebate worth 30 million euros from the French treasury in 2008 while Woerth was budget minister. French investigative magistrates ultimately dropped charges against Sarkozy in 2013 and Woerth in 2015 for lack of evidence.

In May 2015, eight employees, including Banier, were found guilty of swindling more than $1 billion from Mrs. Bettencourt. Banier was sentenced to three years in prison, fined and ordered to pay damages equivalent to $178 million.

Several years earlier, Mrs. Bettencourt told Paris Match magazine that she was aware of Banier’s controlling ways but had no regrets about their friendship.

“I do not want to devalue the irresistible friendship we have had. It’s in the past,” she told the magazine. “François-Marie is madly talented, but he is such a muddler. I couldn’t live with him for more than five minutes, but that muddle in our friendship brought me intense pleasure.”

Liliane Henriette Charlotte Schueller was born in Paris on Oct. 21, 1922. She was 5 when her mother died, and she developed a strong bond with her father, who had begun his business in the early 1900s, manufacturing and selling hair dyes.

By the late 1930s, the L'Oréal empire had expended greatly, and Eugène Schueller used his fortune to help finance an anti-Semitic, pro-fascist political movement called La Cagoule. He gradually aligned himself with the French Resistance during World War II. After the war, he was acquitted of charges of collaboration with the enemy.

In 1950, Liliane Schueller married André Bettencourt, a former member of La Cagoule who was a L’Oréal’s executive and later a French cabinet minister. His wartime record of writing anti-Semitic tracts was exposed in 1994, and he resigned from the company and transferred his remaining shares in the business to his wife.

Mrs. Bettencourt established the Bettencourt Schueller Foundation in 1987; it donates money to French medical research, cultural projects and humanitarian efforts.

In the early 2000s, she was one of the most high-profile victims of financier Bernard Madoff’s Ponzi scheme, losing a reported $25 million. She stepped down from L’Oréal’s board in 2012 and was replaced by a 25-year-old grandson, Jean-Victor Meyers.

André Bettencourt died in 2007. A complete list of survivors was not immediately available.