Adrienne N. Martin (PICTURE): Girlfriend of Ex Anheuser-Busch CEO Overdosed On Oxycodone

(CBS/AP) Adrienne Martin, a 27-year-old aspiring model and the girlfriend of former Anheuser-Busch CEO August Busch IV, died at Busch's home after accidentally overdosing on the painkiller oxycodone, the St. Louis County medical examiner said Wednesday.

Martin, of St. Charles, Mo., was found dead on the morning of Dec. 19 at Busch's sprawling estate in suburban St. Louis after spending the night at his home. He has said he woke up around 11 a.m. and tried to awaken Martin, but couldn't.

St. Louis County forensics administrator Suzanne McCune said the full report from Martin's toxicology exam wouldn't be released until the prosecuting attorney's investigation is complete. She would not say if any other drugs were found in Martin's system.

It wasn't immediately clear if the finding could result in any criminal charges. 

Busch, 46, was the last in a long line of members of his family to head the iconic brewery, maker of Budweiser, Bud Light, Michelob, Busch and other beers. Despite his efforts to ward off a takeover, Anheuser-Busch Cos. Inc. was sold to Belgian brewer InBev in 2008, two years after Busch was named chief executive officer upon his father's retirement.

At Anheuser-Busch, Busch IV earned praise for his role in marketing and advertising that helped Anheuser-Busch control nearly 50 percent of the domestic beer market at the time of the merger. In life, he earned a reputation as a playboy and hard partier.

In 1983, Busch, then a University of Arizona student, left a bar near Tucson, Ariz., with a 22-year-old woman. His black Corvette crashed, and the woman was killed. Busch was found hours later at his home, and he suffered a fractured skull and claimed he had amnesia. After a seven-month investigation, authorities declined to press charges, citing a lack of evidence.

Two years later, Busch was acquitted by a jury in St. Louis on assault charges resulting from a police chase that ended with an officer shooting out a tire on his Mercedes-Benz.

Busch said his relationship with Martin was so strong he had put aside his playboy ways.

"She was the only girl I've ever been with that I didn't want to have someone on the side," Busch told the St. Louis Post-Dispatch in an interview last month. "You know, I'm this notorious bachelor who always wanted someone on the side, but I didn't with Adrienne."

Martin had done modeling work and was the mother of an 8-year-old son from a previous marriage. She was working as an assistant at a small alternative energy firm at the time of her death.

Friends had said she was strongly opposed to illegal drugs. But Busch had previously speculated that medication Martin was taking could have caused her death. He said she was taking Trazodone, a prescription medication to treat depression but also sometimes used to treat insomnia, according to the National Institutes of Health.

Also in the interview with the Post-Dispatch, Busch disputed a contention that there was a 42-minute gap between the time Martin was found unresponsive and a house employee, Michael Jung, called paramedics. Busch said Jung called immediately.

Dec. 27, 2010 - Model Adrienne N. Martin (PICTURE) Found Dead At August Busch IV's Home