On Tuesday (July 29th), Drew Barrymore's paternal half-sister, Jessica, was found dead in a car after what was believed to be a possible overdose, but according to her brother this would have been accidental as she would have not have purposely taken her own life.

Drew Barrymore
Drew's half-sister died from a suspected overdose

Even though the late 47 year-old, who was found in her vehicle parked along a street in National City, Calif., a suburb south of San Diego, had vodka and methamphetamine in her possession, John Barrymore doesn't think she was suicidal.

Jessica's brother, who shares the same father as Drew, told the New York Daily News, "It looks like it was a drug misadventure. Mixing alcohol and pills. I seriously doubt she took her own life."

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"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," he said, referring to the Australian actor's sudden death caused by overdosing on prescription pills in a SoHo loft in 2008.

"It's possible the energy drink and methamphetamine were too much and gave her a heart attack, but I think it was the alcohol plus the narcotic painkillers," John added.

Only hours after the tragic incident, the Hollywood star released a statement to express her grievances, but also revealed that they weren't close with each other. "Although I only met her briefly, I wish her and her loved ones as much peace as possible and I'm so incredibly sorry for their loss," the 39 year-old actress said.

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Shortly after Jessica's body was discovered, National City Police Lt. Robert Rounds said the location of vehicle is rather baffling as "she apparently lived out of the area in northern San Diego County, so she was out of place on that block."

Officials aren't going to reveal the cause of death because results from toxicology tests are still pending, and these could take up to three months to get.