Today the Los Angeles Coroners Office released the results of toxicology reports and revealed the cause of death of actress Brittany Murphy and socialite Casey Johnson.

Brittany Murphy, 32, died of “community acquired pneumonia,” iron deficiency anemia, and multiple drug intoxication, the Los Angeles County Department of Coroner said in a statement released on Thursday.

The L.A. County Coroner concludes on the subject of “How injury occurred” — “Drug intake.” According to the coroner’s office, the death was an accident – but the “injury” occurred because of drug intake. Her pneumonia was listed as the primary cause.

The actress died on December 21, 2009 and a full autopsy report is expected to be released within two weeks.

The Clueless star was found unresponsive in her Hollywood Hills home on Dec. 20, despite frantic attempts by her husband, Simon Monjack, and her mother, Sharon, to revive her.

Simon and Sharon said they believed Brittany’s death was due to a congenital heart murmur and denied rumors that the actress used illegal drugs or suffered from an eating disorder. They added that Murphy’s heart condition was diagnosed in her teens, but said she had received proper treatment for it. They also said that she’d been suffering from laryngitis and flu-like symptoms in the days before her death.

A number of prescription meds were reportedly found by investigators on her nightstand. Simon says his wife was taking the painkiller Vicoprofen and the antidepressant Fluoxetine (also known as Sarafem) to deal with severe menstrual cramps, and that many of the other meds found were for his own use due to a seizure he recently suffered.

The actress was laid to rest in a twilight ceremony in Los Angeles on Christmas Eve.

The cause of death of Casey Johnson has also been revealed and the Los Angeles Coroner has rules the socialite died of natural causes.

The specific cause of death was “diabetic ketoacidosis,” a condition caused by a shortage of insulin, according to a coroner statement. Johnson had suffered from severe diabetes since childhood.

The Johnson & Johnson heiress, 30, who recently got engaged to reality TV star Tila Tequila, was found in her L.A. home on Jan. 4 after lying dead for a few days.

The heiress left behind her adopted daughter, Ava, 3, who will live with Johnson’s mother Sale and her husband Ahmad Rashad “for the foreseeable future,” according to a family source.

Casey was the great-great granddaughter of the founder of the pharmaceutical giant, and the daughter of New York Jets owner Robert Wood Johnson.