The Johnson family wishes to thank everyone who has expressed condolences and support during this trying time. Your thoughts and prayers are deeply appreciated.

The family has arranged for Casey to be flown back east to her final resting place. There will be a private funeral service later this week for the immediate family.

The family asks for a measure of privacy over the next several days as they mourn their loss. No other information will be released at this time.

For the many who have asked what they can do to honor Casey's memory, we ask simply that you consider making a donation to the Casey Johnson Memorial at the Juvenile Diabetes Research Foundation International (www.jdrf.org). Casey struggled throughout her life fighting this disease, and she would want to see all of us continue that fight on her behalf.

“Sweet dreams everyone … I’m getting a new car .. Any ideas?” she tweeted around 1 a.m. on Dec. 29, in what would turn out to be her final update. “Cant b a two seater cause we have a daughter … sedan, sports car, suv??”

Two days before that: “Sooo Excited.. Going to c my Beautiful Fiance very soon … It seems Like its been years that I have not sen her! XX [sic]” (She announced her engagement to reality TV star Tila Tequila last month.)

A few months ago, publicist Lizzie Grubman, for whom Ms. Johnson worked as an intern 10 years ago, visited her in Los Angeles, and they caught up over a sushi lunch. “There are all these rumors about drugs and everything, but I think this was in between her stints in rehab and she looked really good,” Ms. Grubman told the Transom. “She looked like she got her shit together. She was showing me pictures of her daughter and she said she was single, and she was actually talking about possibly moving back to New York. At that point, I felt like she was in a better place than I had seen her in a long time.”

But soon after that meeting, amid reports of Ms. Johnson’s increasingly strange behavior, Ms. Johnson’s mother, Sale Johnson, swooped in and took custody of Casey’s 3-year-old daughter, Ava, who was adopted from Kazakhstan in 2007. Johnson mère also reportedly restricted Casey’s access to family money. Casey wanted her daughter back desperately and, according to friends, was ready to give rehab another go.

Alas, on Monday, Jan. 4: “At about 11:51 in the morning, our Wilshire area patrol officers responded to what we call an ambulance death investigation in the 900 block of North Orlando Avenue,” officer Sara Faden told the Transom. “Los Angeles City Fire Department also responded and pronounced Ms. Casey Johnson dead at the scene. The preliminary death investigation reveals that it appears to be a natural death, as there is no evidence of foul play. There was no forced entry or any weapons nearby. There does not appear to be any sort of crime. The coroner’s office is now taking on the investigation and they will conduct their screening, including a toxicology report, to determine if other factors led to her death.”

Ms. Johnson was 30 years old. Homicide investigator Javier Hernandez, who is working the case, told the Transom that the coroner’s office will likely take six to eight weeks to produce a thorough report.

Born Rich documentarian Jamie Johnson, Casey’s uncle, and other family members did not respond to phone calls. “The Johnson family is mourning its tragic loss,” a representative wrote to The Observer in an email, “and asks for privacy during this very difficult time.”

Ms. Johnson started out much like the city’s other heiresses. Her parents were Robert Wood “Woody” Johnson IV, the great-grandson of the pharmaceutical company founder, who bought the New York Jets in 2000 for $635 million, and former model Nancy Sale Frey. (They are now divorced.) She grew up on Fifth Avenue and 64th Street. “Casey was brought up in the building where we live, so I knew her as a child,” the socialite Susan Gutfreund told the Transom. “Casey was a golden girl, and I’ll miss her terribly. But that’s really all I can say. I’m really upset.”

Ms. Johnson attended Chapin; a former classmate, who asked not to be named, told the Transom that as a schoolgirl, Ms. Johnson was obsessed with Madonna and wanted to emulate her. Mike Heller, the nightclub promoter–turned–marketer, who dated Ms. Johnson for three years when she still lived in New York, said she also used to talk about Marilyn Monroe as her icon.

Casey subsequently attended Marymount and Dwight (with Paris Hilton) for high school and then Brown University, but she dropped out her freshman year. Ms. Johnson took a number of jobs, including teaching singing at Dwight, and the stint for Ms. Grubman.  

“She was really a good girl and very misunderstood,” said Ms. Grubman. “She was misdirected. She was always trying to find something for herself. When she worked for me, she wanted to make something of herself, but I don’t think she ever necessarily knew what that was. She just wanted to make her family proud, but she just didn’t know how to do that. Her and her mother were best friends and went everywhere together. They were inseparable.”

But New York socialites are no longer content to be demure, pretty ladies at debutante balls. Ms. Johnson posed in Vanity Fair in 2006 with a cigarette and nothing but a gauzy scarf draped across her front; she took to Page Six to accuse her aunt, Libet, of stealing her boyfriend; she began dating Yahoo! CEO Terry Semel’s daughter, Courtenay (previously linked to Lindsay Lohan), who later allegedly set Ms. Johnson’s hair on fire during a fight; and she was recently charged with grand theft after allegedly breaking into model Jasmine Lennard’s Hollywood home, stealing clothes and jewelry and leaving a used vibrator on the bed. In the end, Ms. Johnson seemed closer in sensibility to her fiancée, Ms. Tequila, than she was to her childhood classmates.

Perhaps that transformation was attributable to that big, bad city of Los Angeles that ingests educated, humble young people and spits out Heidi Montags.

“She was a very giving, kind person when I knew her,” said Mr. Heller, who last saw Ms. Johnson at the Beverly Hills hotel six months ago. “She ran the junior diabetes foundation. She came on a trip with me to Mexico and wanted to visit the hospitals there. I think when she moved to L.A., it really affected her in a bad way. We talked over the phone a couple of weeks ago and she seemed fine. But obviously she was not fine.”

A Los Angeles cop, who was said to be fearful for his safety, pulled a gun on P. Diddy and his entourage during a routine traffic stop. [NY Daily News]

Casey Johnson, the billionaire heiress previous linked to Courtenay Semel, showed up at Kathy Lee Gifford's 55th birthday party with a new girlfriend named "Lisa," who was wearing a leather trench coat. [P6]

While Jennifer Aniston has split from Cameron Diaz's ex, John Mayer, Ms. Diaz is still enjoying the company of Ms. Aniston's ex, Paul Sculfor. [P6]

Lindsay Lohan and Samantha Ronson shopped for baby clothes yesterday, but the sales staff of the baby boutique said that neither was pregnant. [NY Daily News]

Michelle Williams is reportedly officially dating her close friend director Spike Jonze, who was previously married to Sofia Coppola. [Daily Mail]  

Vogue intern and New York Ranger Sean Avery, 28, is dating 51-year-old Kelly Klein, ex-wife of Calvin. [P6] 

In the ongoing custody battle between Ron Perelman and Patricia Duff, their 13-year-old daughter Caleigh is refusing to speak to her mother or go on vacation with her, according to the Manhattan judge handling the case. [NY Daily News]  

Not kosher: Former Real World contestant Kevin Powell, who is running for Congress, told an audience of Hasidic Jews Monday night that he would "bring home the bacon." [P6] 

Alex Rodriguez is working things out privately with wife Cynthia regarding visitation rights and alimony payments in order to avoid having to admit to his extramarital affairs in court. [NY Daily News] 

Katie Holmes has arrived in Manhattan to prepare for Arthur Miller's All My Sons, which will premiere on Broadway September 17. [Us Weekly]

NYC Council member Tony Avella is accused of receiving a bouquet of flowers from Pamela Anderson. Quelle scandale! [Politicker] 

If Old Guard Society always prided itself on being well known but invisible, much of the younger generation has seemingly tilted far in the direction of relentless visibility. Ms. Johnson, who says her favorite restaurants are McDonald's and Harry Cipriani, has been dipping a toe in both worlds, perhaps charting a course of sorts for her moneyed peers. "She's definitely way ahead of her time," said Manhattan File publisher and editor Cristina Greeven. "She's not limited by having grown up in the Johnson and Johnson family, in a sheltered environment. She acts as a bridge between everybody."

"She's a very sophisticated little girl," said Noah Tepperberg, an owner of the Conscience Point nightclub in Southampton. This past summer, Ms. Johnson would finish off a day at the polo matches and an evening at a charity benefit by dancing on the tables at Conscience Point with her childhood friends the Hilton sisters, Paris and Nicky. "There's something really interesting about her," said Mr. Tepperberg. "She has that old-guard charm and is also sort of young."

Ms. Johnson attributes whatever maturity she may have to having been diagnosed with insulin-dependent diabetes when she was 8 years old during a routine check-up. She gives herself insulin shots every day and often has to lie in bed for hours if her blood sugar is too high or too low. "When you're diagnosed with a disease at an early age, you're forced to grow up," she said. Ms. Johnson was sitting on a white fluffy couch in the Lafayette Street offices of the publicity firm Lizzie Grubman-Peggy Siegel company, where she works three days a week. She was dressed in a magenta tank top, brown slacks and brown Chanel wool flats, looking like a dainty society lady crossed with a teenage diva. One moment, she sounded like a seasoned philanthropist; the next, she might put her small hands to her face and giggle.

"Everyone has their thing they deal with," she said of her diabetes. "But hopefully, with so many new things coming out … " She regularly works out with a trainer and does yoga. "Unfortunately, I love Cool Ranch Doritos. That's my downfall," she said.

While the Hilton sisters are using their heavy-hitting last name and brimming bank accounts to launch a cosmetics line, Ms. Johnson has committed herself to raising money for health issues. Her big event of the year is the Promise Ball, a Juvenile Diabetes Foundation fund-raiser she's helped organize for the past several years. This year, she's on the committee with Mary Tyler Moore and Miramax Films honchos Harvey and Bob Weinstein. It's on Nov. 11 at the Waldorf Astoria–the same place where she had her debutante ball in 1998. Her father, Robert (Woody) Johnson IV, who bought the New York Jets football team earlier this year for $635 million, is the international chairman of the Juvenile Diabetes Foundation. He is also the chairman of the Alliance for Lupus Research–Ms. Johnson's 13-year-old sister was recently diagnosed with that disease.

Her task at the Lizzie Grubman-Peggy Siegel company is basically to get her high-profile friends to attend events being publicized by the firm. That morning, Lizzie Grubman had asked Ms. Johnson to wrangle some of her close pals into attending that evening's opening party for Light, a lounge on East 54th Street.

Who does she decide to invite from her Louis Vuitton Filofax? "It depends on the event," Ms. Johnson said. "If it's for Puff Daddy, I'm not going to call my grandmother and say, 'Hey granny, come to Puffy.' If it's appropriate, I'll call my mother, I'll call [socialite] Helen Downey, a wonderful friend of mine."

On a recent Saturday, Ms. Johnson was with about 25 wonderful friends at 21, where they were celebrating her 21st birthday. She was wearing an animal-print dress, and the table included her parents; her godmother, Diandra Douglas; producer Marty Richards (who was once married to Ms. Johnson's great aunt, Mary Lee Johnson); Nicky Hilton; and jewelry company heiress Elisabeth Kieselstein-Cord. The next morning, Ms. Johnson would fly to Tampa, Fla., with her father to watch a Jets game.

Dropping Out, Going Out

Ms. Johnson was born in Florida, and her parents moved into the Sherry Netherlands Hotel when she was 3 years old, before buying an apartment at Fifth Avenue and 64th Street. "I went to a couple of high schools," she said, laughing. She found the Chapin School "really competitive. It wasn't an incredibly nice, warm atmosphere." When she was 14, she and her parents co-authored a book, Managing Your Child's Diabetes. Her godmother, Ms. Douglas, took her fox-hunting in New Jersey. ("She's the daughter I never had," said Ms. Douglas.) She graduated from the Dwight School, then attended Brown University for one year before dropping out last May. "School was not my thing," said Ms. Johnson. "I have a very strong friendship with my dog," she said, about her black poodle, Zoe. "She wasn't allowed with me, and that really , really upset me. I bring her to dinner, movies. That was really hard, and I wasn't into it." So she moved into a one-bedroom apartment near the Whitney Museum of Art and did some decorating. "It looks like somewhere my parents would live," said one friend.

And so Ms. Johnson's relatively old money began to mix with the new.

"I think she was already pals with my mother before I was actually friendly with her," said Chris Barish, the 27-year-old co-owner of Light and son of movie producer Keith Barish. "Casey has always been extremely social and precocious. I think she has a spirit of a younger generation, yet she was raised extremely well, with a lot of adults, in a sophisticated setting. She's managed to marry young and old with a lot of style."

"She has that classic kind of style," said Eleanor Lembo, a fashion assistant at Lucky magazine. "But she's totally fun and spunky and loves to have a good time. She was brought up very well. If I have a question like 'Do I send a thank-you note?', she always knows."

A social Upper East Sider who wished to remain anonymous said that Ms. Johnson differs from some of her less blue-blooded friends because "she's from a major, major family. Of course, she conducts herself in different way." The socialite blamed nightclub promoters for propelling young social women "into mini-stardom" without knowing if a person is worth "$5 million or $200 million."

Ms. Johnson says she is currently single. A two-year relationship with Michael Heller, now 24, a law student and club promoter, ended last winter. Mr. Heller said Ms. Johnson struck him as "two different people. One minute she'd be childish, naïve, and all of the sudden she'd change and be worldly, well-poised, well-spoken."

Mr. Heller said that Ms. Johnson had many endearing qualities. Once she invited him over to dinner, telling him she had cooked his favorite meal. "I'd come over all excited," he said, "and she'd say, 'Didn't I do such a good job?' Then I'd walk into the kitchen and see the bags and realize she had ordered it from Ferrier," a bistro on East 65th Street.

"He never confronted me about that," said Ms. Johnson, laughing. She added that she once told Mr. Heller she had "slaved away all day" over a birthday cake for him, when in reality it had been baked by her parents' chef. "I don't think he knows to this day that I didn't make it," she said.

These days, a typical week for Ms. Johnson might involve the opening of the Hermès store on Madison Avenue, a party for Bobbi Brown's teen beauty book and a book party for Liz Smith at Le Cirque.

Ms. Grubman said Ms. Johnson got her job at the publicity firm on her own merits. "She made it proper, she made an appointment for an interview," said Ms. Grubman, adding, "She's done a phenomenal job."

"I think Casey really found her niche," said Ms. Cord about Ms. Johnson's job. "She has the most amazing people skills. She's like a little butterfly; there's a light inside of her."

Ms. Johnson said she did find it a bit unsettling that her junior set's socializing has become such tabloid fodder.

"It's a little weird, seeing your friends in the tabloids," she said. "When I started going out and reading the paper when I was 14 or 15, which I never did before, and started seeing people I knew in the paper, I was like ' Oh, my God .'"

She has not surfaced herself as a New York Post Page Six character, and perhaps it is worth noting that Ms. Johnson and her friends more closely associate themselves with the more subdued 17-year-old Nicky Hilton than with the more outrageous 19-year-old Paris Hilton.

Seasoned socialite Nan Kempner felt that her generation's legacy was safe. "They all look so beautiful, and it's nice to see an eager-beaver set," said Ms. Kempner about Ms. Johnson and her friends. "I'm sure they'll be very successful and very charitable. I'm sure we can turn over the reins of the benefits to these bright young things. It's called evolution."