Barrymore's half-sister died from overdose

• Jessica Barrymore, 47, was found dead in her vehicle on July 29


• She had methamphetamine, alcohol, methadone, tramadol and nordiazepam in her system


• Jessica and Drew Barrymore are both daughters of actor John Drew Barrymore

(CNN) -- Jessica Barrymore, the half-sister of actress Drew Barrymore, died from an accidental drug overdose last month, a coroner's report said Tuesday.

Jessica Barrymore, 47, was found dead in her vehicle on a street in National City, California, near San Diego, on July 29, the San Diego County Medical Examiner said in a report.

Toxicology tests revealed that she had methamphetamine, alcohol, methadone, tramadol and nordiazepam in her system, according the San Diego County Medical Examiner.

Barrymore was found at the wheel of a car blocking her driveway, the report said.

Jessica Barrymore and Drew Barrymore are both daughters of actor John Drew Barrymore but have different mothers.

Drew Barrymore, who was born nine years after Jessica, met her half-sister only "briefly," she said in a statement. She expressed sorrow at her death.

"I wish her and her loved ones as much peace as possible and I'm so incredibly sorry for their loss," she said.

CNN's Topher Gauk-Roger contributed to this report.