Five Things You Need to Know About the Late Casey Johnson

Heiress's untimely death leaves many questions unanswered. Here is our quick primer on her life

The short life of socialite Casey Johnson is over.

While she had lots of celebrity friends, the 30-year-old Johnson & Johnson heiress was not a household name.

So who was she exactly? You might be surprised. Here are five things about Johnson you need to know:

• She Was a Published Author: After battling childhood diabetes, Johnson and her New York Jets-owning father, Robert Wood Johnson IV, cowrote a book called Managing Your Child's Diet.

• She Had Celebrity Pals, Including Paris and Nicky Hilton: The Hilton and Johnson families are longtime friends, and the daughters remained close until Casey's untimely passing. The three socialites grew up having playdates and parties together.

• She Had an Adopted Daughter: Johnson brought Ava Monroe—named after her idol Marilyn Monroe—home from Kazakhstan in 2007. Ava calls Nicky Hilton her godmother, but reports state that family members worried the heiress did not care well enough for her daughter, forcing the child's grandmother Sale Johnson to take her in.

• She Had a Recent Arrest Record: In November 2009, Johnson was arrested on charges of grand theft, a felony, after allegedly stealing jewelry, clothing and a legal document from an ex-girlfriend. She was arraigned on Dec. 21 and officially charged with two counts: first degree residential burglary and receiving stolen property. She pleaded not guilty and was due to appear for a preliminary hearing next month, though the charges will now be dropped.

• She Was Engaged to Reality Star Tila Tequila: Johnson had a tumultuous, on-off relationship with Courtenay Semel (check out a portion of E! News' interview with Semel below), who also happens to be an ex-girlfriend of Tequila. In December 2009, the plot thickened when Johnson and Tequila announced their engagement at a red carpet event. Following her fiancée's death Monday, Tila tweeted: "Everyone please pray 4 my Wifey Casey Johnson. She has passed away."