Despite a history of addiction, the actress--whose body was discovered in her mobile home by a neighbor last September--was originally believed to have died from natural causes. Her death came a week shy of her 47th birthday.
But toxicology tests released Wednesday reveal O'Grady died of "multiple drug intoxication," the coroner said. Fatal levels of the prescription painkiller Vicodin and the antidepressant Prozac were found in her bloodstream.
The coroner said it was undetermined whether the overdose was accidental or a suicide.
Although O'Grady retired from acting in the '80s to become a talent agent like her mother, she long ago secured her place in the TV Land pantheon as Mary, the braniac wannabe doctor in Eight Is Enough's expansive Bradford brood. The dramedy, starring Van Patten as a newspaper columnist and superdad, ran on ABC from 1977-1981.
Aside from her four-year stint on the show and two late-'80s Eight Is Enough reunion specials, O'Grady racked up appearances on such other '70s tube staples as The Love Boat, as well as TV movies like The Kid with the Broken Halo, before leaving Hollywood.
She had been dogged by health and pill problems dating back to her Mary Bradford days. In a series of interviews in the 1990s, she admitted to having suffered panic attacks for the previous 20 years. Scores of doctors misdiagnosed her; to cope with the frequent anxiety episodes--sometimes she'd shake so badly she couldn't leave her dressing room to shoot a scene--she was fed a veritable pharmacy: Xanax, Valium and Librium. She became hooked on the pills and, eventually, alcohol, too.
"I drank two bottles of Chardonnay a day, took a ton of prescription pills," she told Geraldo Rivera during a 1994 interview. She went into rehab at least five times.
By the mid-'90s she declared herself clean, thanks to an alternative-medicine regimen, and even went to work for her doctor as a recovery counselor.
But, in 1998, she checked herself into the mental health ward of Cedars-Sinai Medical Center for detox. She had become hooked on a prescription drug called Ativan. While in Cedars, she claimed she was sexually battered by a medical technician and sued the hospital. The suit was pending at the time of her death.
O'Grady came from a show-biz family. Her brother, Dan Grady, was an original Mouseketeer and member of another notable TV family--he played Robbie on My Three Sons. Her mother, Mary Grady, was a noted agent who represented several child actors.