Christopher Nowinski, a former pro wrestler who now is president of the Sports Legacy Institute, said concussions can happen in the World Wrestling Entertainment league even though many of the moves are staged.

"I got four concussions in three years as a professional wrestler," said Nowinski, who works as an independent contractor for the WWE. "A lot of concussions happen from mistakes."

The district attorney overseeing the death investigation has said Benoit strangled his wife with a cord, used a choke hold to strangle his 7-year-old son, then placed Bibles next to the bodies and hanged himself on a piece of exercise equipment in his home the weekend of June 22.

Authorities have said that Chris Benoit's personal doctor, Phil Astin, prescribed a 10-month supply of anabolic steroids to Benoit every three to four weeks between May 2006 and May 2007.

Testosterone can be used as part of hormone replacement therapy. Some athletes also have been known to use steroids to enhance their performance.

Astin has pleaded not guilty to federal charges of improperly prescribing painkillers and other drugs to two patients other than Benoit. Federal prosecutors plan a superseding indictment with new charges, but haven't said when they will act.

The GBI conducted an autopsy and toxicology tests on the bodies, but analyzing Benoit's brain was not part of the examination, spokesman John Bankhead said Wednesday.