Despite her life of privilege, socialite Casey Johnson struggled in the fast lane

Casey Johnson was an heiress to one of the world’s great fortunes, grew up privileged in Manhattan with socialite sisters Paris and Nicky Hilton and eventually moved to Los Angeles, where she became a familiar face on the Hollywood party scene.

But amid a gilded existence, Johnson also struggled.

She was diagnosed with diabetes, battled drug addiction, had strained relations with her family and last month was hit with criminal charges for allegedly breaking into the home of a girlfriend and taking $22,000 in property.

On Monday, the 30-year-old was found dead at her Westside home.

Los Angeles police officials said they don’t believe Johnson’s death was a result of foul play, but a definitive cause won’t be clear for more than a month, according to Ed Winter of the Los Angeles County coroner’s office.

A preliminary investigation by police homicide investigators found nothing to suggest that Johnson died of anything other than natural causes.

And sources with the Los Angeles Police Department -- who spoke on the condition that they not be named because of the ongoing investigation -- believe the cause was “medically related.”

An autopsy performed Tuesday was inconclusive and the cause of death was deferred four to six weeks, pending the outcome of toxicology tests, Winter said.

He said his office had received information that Johnson had a history of diabetes, but could not immediately say what role, if any, it played in her death.

“We are still conducting our investigation,” Winter said.

The personal life of Johnson, the daughter of New York Jets owner Woody Johnson and the girlfriend of reality TV star Tila Tequila, has long been a staple for celebrity gossip sites and tabloids including Page Six, which dubbed the heiress to the Johnson & Johnson empire the “baby-oil heiress.”

Johnson called it “the stupidest mistake of my life” to turn down an invitation from pal Paris Hilton to costar on “The Simple Life.” The role went to Nicole Richie.

Johnson was featured on “It Girls,” a 2002 documentary about the young and rich in Manhattan.

There were signs of strain in Johnson’s life in the last few years.

She became locked in a struggle with her mother over custody of Ava-Monroe, a baby born in Kazakhstan who was adopted by Johnson in 2007.

Most recently, Johnson was arrested and charged in December in connection with a break-in at the home of Jasmine Lennard, another reality television star and former girlfriend.

Johnson was charged with first-degree residential burglary and receiving stolen property for allegedly taking $22,000 in clothing, jewelry, handbags, personal mail and other items. She pleaded not guilty and was due back in court Feb. 11 for a preliminary hearing.

On Tuesday, friends expressed sadness about her untimely death.

“I feel so sad right now, my heart is in pain. Just lost a longtime friend. My heart goes out to her family. R.I.P. Casey Johnson,” Paris Hilton wrote on her Twitter page. “In bed crying, looking at baby pictures of Casey, Nicky and I. I feel so upset. I feel like I’ve lost a sister. My heart is broken.”

andrew.blankstein @latimes.com