Drew Barrymore's half-sister, Jessica Barrymore, died of an accidental drug overdose, according to a coroner's report.

Last month, Jessica was found dead at age 47 in a parked car in National City, California. San Diego County Medical Examiner revealed Tuesday that toxicology tests found "alcohol, methamphetamine, methadone, tramadol and noriazepam" in her system when she died, the New York Daily News reported. 

Authorities were called on July 29 by one of Jessica's neighbors who claimed that she was unable to get to work because Jessica's Toyota Camry was blocking her driveway. She was pronounced dead on the scene when police found "vodka, meth and pills" near the passenger seat of her car, reported NBC.

The actress and her half-sister are both daughters of actor John Drew Barrymore; however, both siblings have different mothers. The two only met twice, according to the Daily News.

Her older brother, John Barrymore, said that his sister's death was a "drug misadventure" and not a suicide, adding that "there were some empty vodka bottles, a couple bags of meth and a variety of pills in the car. My guess is that it was the booze and pills, like with Heath Ledger."