Frank Sinatra's widow Barbara passes away aged 90 in California ... almost 20 years after the death of her legendary husband

• e-mail

Barbara Sinatra passed away on Tuesday at her home in California.

The former model and fourth wife of Frank Sinatra was 90, and had been in declining for several months.

Barbara became one of the most famous women in the world when she married Sinatra in 1976, spending 22 years with the singer before he passed away in 1998 at the age of 82 from a heart attack. 

She leveraged the fame afforded to her by way of her marriage to raise funds and rally support for a number of charitable causes, most notably the Barbara Sinatra Children's Center at Eisenhower Medical Center.

Opened in 1986, the center aids victims of child abuse, and is almost entirely funded by the money raised at the annual Frank Sinatra Celebrity Invitational Golf Tournament.

Barbara also carefully controlled the legacy of her late husband, and in 2015 oversaw the release of a coffee table book featuring a collection of the 'My Way' crooner's personal photos entitled 'Sinatra: The Photographs.' 

Scroll down for video

They did it their way: Barbara Sinatra died on Tuesday at the age of 90 at her house in California (above with Frank in 1990)

Love and marriage: Barbara and Frank cut into their wedding cake after their 1976 marriage (above)

Luck soup: Barbara was just 29 when she married 58-year-old comedian Zeppo Marx (above in 1959)

The Desert Sun was the first to report the news of Barbara's death. revealing that her final moments were spent surrounded by friends and family at her Rancho Mirage home.

Nancy Marx was a prominent Palm Springs socialite log before she wed Ol' Blue Eyes, though it was her beauty and not a family fortune that earned her a spot in that rarefied group.

She was born in Bosworth, Missouri in 1927 and did not move out to California until her late teens, settling with her mother in Long beach after being accepted to the Robert Edward School of Professional Modeling.

Barbara at Frank's funeral in 1998 (above)

Her modelling career quickly took off, and she caught the eye of many a suitor, but quickly settled down with her first husband.

Barbara was also no stranger to the wedding aisle either, having made two trips to the altar prior to her marriage to Frank.

It was shortly after moving to California that she met and married Robert Harrison Oliver, a band singer, and found herself in New York City.

She was accepted by the country's premiere modelling agency, Ford, and began racking up jobs in premiere fashion magazines such as Vogue.

Barbara also became pregnant, and gave birth to her first and only son Robert. 

Her husband was not finding success however in New York and it quickly became too much for Barbara to support the family on her own, so they headed back to California.

Barbara opened her own modelling agency there but her marriage soon disintegrated when she was caught having an affair, at which point she made the move to Las Vegas.

It was while performing as a showgirl in Sin City that Barbara met her second husband, Zeppo Marx. 

He was quickly smitten with Barbara and whisked her away from the Vegas Strip and back to California, putting her up at a motel next to the famed Racquet Club in Palm Springs.

Strangers in the night: Barbara and Frank with Ronald Reagan and wife Nancy at a 1980 fundraising event for the future president (above)

The lady is a tramp: Barbara at the 100th anniversary of the Statue of Liberty with Liza Minnelli and Veronique Peck in 1986

I've got you under my skin: Barbara is joined by Robert DeNiro at the Frank Sinatra Las Vegas Celebrity Classic just two weeks after her husband's death in 1998

It was a very good year: Barbara is honored by Sidney Poitier and Jamie Foxx while beiung honored at the Seventh Annual Rick Weiss Humanitarian Awards in 2005

You make me feel so young: Barbara and Kirk Douglas at the Juvenile Diabetes Research Foundation Annual Gala at Beverly Hilton Hotel in 2007

Robert meanwhile was shipped off to a military academy, which was paid for by Marx.

He and Robert grew incredibly close over the years and Marx had hoped to adopt the boy and legally make him his son, but his father refused to grant that request.

Marx and Barbara were married in 1959 at the Riviera in Las Vegas, the same hotel where Zeppo first saw his future bride dancing. 

One for my baby: Barbara and son Bob Marx

They spent over a decade together, during which time Barbara got to know one of their neighbor's in Rancho Mirage - Frank.

She detailed their first meeting in their memoir, and said even then she kne the two would be together. 

'My first encounter with the fiery Italian side to Frank Sinatra came during a late-night game of charades. His pals were divided into two teams, and I was put in charge of a big brass clock. So, naturally, it fell to me to call time on Frank's team after they'd failed to guess his charade.

'Three minutes are up,' I cried gleefully.

'His team-mates began to howl their protests, but the look on Frank's face as he rose to his feet silenced them all.

'"Who made you timekeeper anyway?" he barked, his eyes like blue laser beams.

'"Why, you did!' I replied.

'Frank snatched the clock from my lap and gripped it tightly in his hands. For a moment, I thought he was going to hit me with it. His expression was full of anger and frustration, but there was something else — desire. I think I knew then that something would happen between us someday.

'Still, I refused to be intimidated. So I stared him out until he turned and hurled the clock against the door, shattering it into pieces.' 

Summer wind: Barbara and Frank in 1973 at the time her divorce from Zeppo was being finalized  (above)

Fly me to the moon: Frank and Barbara on vacation in Monaco in 1984 (above)

Moon river: Frank and Barbara at the Southern California Foundation for the Developmentally Disabled event in LA in 1982

Barbara wrote in her memoir that Marx was an incredibly jealous and possessive husband, who would snap if he caught her so much as talking to another man.

These strong feelings did not stop Marx from having his own affairs, and eventually Barbara and Frank began having seeing one another in private.

Marx and Barbara split and were granted a divorce in 1973, at which point she and Sinatra had already made a very public display of their relationship. 

She said it her way: The star, seen here in 2005, wrote about Frank in her tell-all

She then converted to Roman Catholicism before marrying Frank in 1976, with the two enjoying a long and happy union. 

Barbara had previously told the Desert Sun she was never sure why Frank wanted to marry her instead of another star like third wife Mia Farrow or second wife Ava Gardener.

'I’ve tried to analyze it,' she said.

'I think it’s because we were friends before anything romantic happened. He would call and chat, but it wasn’t romantic until later. It’s something you can’t explain why or how it happened.' 

There is no one Frank trusted more however, which was made very clear in his final will and testament, which left almost everything to Barbara.

She received over $3million, three California mansions (in Beverly Hills, Malibu and Palm Springs), the rights to Sinatra's legendary 'Trilogy' recordings and complete control over her husband's name and likeness. 

It was her work helping abused children that most defined her life however, and not her husband. 

John Thoresen, director of the Barbara Sinatra Children’s Center, said more than 20,000 children have been treated at the center in the desert city of Rancho Mirage and hundreds of thousands more throughout the world through videos it provides.

Over the years, Frank and Barbara played an active role in the children’s center.

'Frank would come over and sit and read to the kids,' Thoresen said of the sometimes volatile entertainer.

'But the best way she used Frank, was she would say, "I need a half-million dollars for this, so you do a concert and I get half the money.”'

She remained active at the center until recently, pushing for creation of the video program just last year and making sure the children had anything they needed said Thoresen.