Casey Johnson

Casey Johnson once said she saw "a lot of similarities" between her and her doomed idol, Marilyn Monroe.

"Her life makes me sad. I don't think she was very happy. She was just very, very complicated and sort of a deep person, and nobody realized that," Johnson told Vanity Fair in 2006. "They thought she was some dumb blonde, and she wasn't. She was a smart, smart broad. And I think that sometimes people look at me and think, Oh, Casey Johnson, she's stupid, she's blonde, she's an heiress, blah, blah, blah."

Casey Johnson dead at 30

Like Monroe, Johnson died young. The 30-year-old heiress to the Johnson & Johnson fortune and daughter of New York Jets owner Woody Johnson was found dead at her Los Angeles home on Monday. Her body was undiscovered for days, TMZ reports. A cause of death has not been determined, pending toxicology reports, but authorities say it appears to be natural — to the extent that any 30-year-old's death can be considered natural. An autopsy was pending, Ed Winter, chief coroner of the L.A. County Coroner's Office, told TVGuide.com.

Johnson's premature death capped off what Johnson described as a misunderstood life of luxury, addiction and scandal — a lonely end for a hard-partying socialite who counted Paris and Nicky Hilton and Bijou Phillips as friends. Though a product of one of the most prestigious families in the country, she ran with a circle of nightclub fixtures.

One of them, Lindsay Lohan, remembered Johnson in a typically jumbled tweet: "r.I.p. To a friend to and of many — Casey Johnson — my regards to her family, friends and her beautiful daughter Ava* you are in our hearts CJ."

"In bed crying, looking at baby pictures of Casey, Nicky and I. I feel so upset," Paris Hilton tweeted in a message displayed over her standard backdrop, a picture of herself in a red corset, heels, and fishnets. "I feel like I've lost a sister. My heart is broken. Miss her."

Raised on Fifth Avenue, Johnson was privileged from birth, getting her first Chanel bag at age 10 and her first car before she even had her license. Like Monroe, she tried to conceal a side that belied the posh stereotypes she felt the world didn't see.

Diagnosed with diabetes at the age of 8, Johnson co-wrote a book with her father called Managing Your Child's Diabetes in 1994. She later supported her father's organization, the Juvenile Diabetes Research Foundation, among other charities. "It's so boring to do nothing. ... And you feel like s--t," she told Vanity Fair. "You think, What have I ever done to alter this world? What will people say? 'Oh, she had a lot of shoes'?"

See the other celebrities we lost in 2009

After dropping out of Brown University, she worked for publicist Lizzie Grubman, and was present on the 2001 night Grubman backed an SUV into a crowd of people waiting outside the velvet ropes of a Hamptons nightclub. Johnson later worked as a beauty editor for the now-defunct Manhattan File magazine — a job she said she loved despite the "measly paychecks." "[It was] great to have someplace to be where you're needed," she said.

She wanted to be a serious actress, but deferred instant celebrity when she turned down the chance to be Paris Hilton's sidekick on The Simple Life. Hilton, she said, loved attention, but she didn't. She later called the decision "the stupidest mistake of my life" after seeing all the windows of opportunity the show opened for Hilton's ultimate Life partner, Nicole Richie.

Johnson, who did appear on The Fabulous Life Of... and in the 2002 documentary The It Girls, eventually gained notoriety for her substance abuse, failed trips to rehab, and she-said, she-said feuds. She denied reports that she caused a brawl between Phillips and Playboy Playmate Nicole Lenz at a 2004 MTV party.

"Drama seems to kind of surround me," she told Vanity Fair.

In 2006, Johnson publicly accused her notoriously private and five-times married aunt, Libet Johnson, of seducing her then-boyfriend, John Dee, exercising none of the prim-and-proper high-society decorum Libet Johnson exemplified.

Though friends believed the incident would force Johnson to turn her life around, more familial turmoil was ahead for the celebutante. Her father cut off her trust fund and her mother, Sale Johnson, took custody of her 3-year-old daughter, Ava-Monroe (named after Marilyn Monroe), after Johnson repeatedly failed to clean up her act and was discovered to be living in squalor, the New York Post reported last month.

Tila Tequila engaged to Johnson & Johnson heiress

Also last month, Johnson and Tila Tequila announced their engagement in an online video with the Shot at Love star flashing a 17-carat ring. The announcement came soon after Johnson's Nov. 30 arrest on felony charges of theft and receiving stolen property. She was accused of taking jewelry, underwear and other items from ex-girlfriend Jasmine Lennard, a model and star of such British reality shows as Make Me a Supermodel.

"The truth is that she needs to get serious help," ex-girlfriend Courtenay Semel told the Post at the time. "But what worries me is that she will hit rock bottom before she does that."