Casey Johnson post mortem inconclusive.

A post mortem to try to find the cause of death of heiress Casey Johnson has been inconclusive.

There were no visible signs of trauma, the LA County Coroner’s Office said, ruling out foul play.

Toxicology tests are being carried out but the results may not be known for some weeks.

The 30-year-old heir to the Johnson & Johnson fortune was found dead in Los Angeles on Monday but may have died several days earlier, police say.

She reportedly suffered from diabetes and had apparently twice been admitted to hospital after falling into a diabetic coma.

Reports also suggest that a number of prescription pills were also found in her apartment although police have refused to comment on this.

Johnson was notorious for her hard-living. Her drinking binges and rows with her girlfriends made her a regular in the tabloid press.

Friends including Paris Hilton have been remembering her on Facebook and Twitter.

Hilton wrote: “I feel so sad right now, my heart is in pain. Just lost a longtime friend. My heart goes out to her family. RIP Casey Johnson. Love you.”

Johnson’s most recent relationship was with fellow TV reality show star Tila Tequila, to whom she apparently became engaged in December.

She wrote on Twitter: “I can’t stop these haunting visions of her and I. We made such a lovely couple, only beginning to spend the rest of our lives together.”

A statement issued on behalf of Johnson’s family said: “The Johnson family is mourning its tragic loss, and asks for privacy during this very difficult time.”