Designer Steroid Doping Scandal

The witness list reads like a who's who of elite sport: sprint champion Kelli White, Yankee first baseman Jason Giambi and San Francisco slugger Barry Bonds.

And, as CBS News Correspondent John Blackstone reports, they're just a few of the top athletes summoned before a federal grand jury investigating nutritional supplement salesman "to the sports stars" Victor Conte.

"You have the NFL, you have Major League Baseball, you have track and field - that really makes it probably the most far reaching scandal in the history of sports," says Sports Illustrated's Roy Johnson.

Conte's company, BALCO Labs, has been named by anti-doping authorities as the likely source of the designer steroid THG: a drug that until recently was undetectable.

Conte has denied supplying THG but his Web site does claim to do wonders for athletes with his "inductively coupled plasma spectrometer": a machine he uses to test for nutritional deficiencies.

BALCO claims that through precise testing it can adjust an athlete's diet at the micro nutrient level, helping athletes achieve what they have never achieved before.

But nutritionists like Douglas Calman, of the American College of Sports Medicine, are skeptical.

"It would be an amazing discovery-probably on par with Ponce de Leon looking for the fountain of youth," says Calman.

Still, BALCO's modest offices have become almost a shrine for top athletes.

Bonds has added substantial muscle since his early days in baseball. He credits weight training and BALCO's nutritional supplements. Giambi, another Conte client, has become noticeably more muscular.

Conte's apparent success with elite athletes has helped him sell millions of dollars in nutritional supplements to the general public. His biggest seller is a zinc and magnesium supplement he claims increases "hormone levels and muscle strength".

But David Lightsey of the National Council Against Health Fraud says no supplement can build substantial amounts of new muscle.

"That only indicates one thing to me and that's steroid use or growth hormone," says Lightsey.

Now, investigators are trying to discover whether, under the guise of better nutrition, Conte has been helping star athletes beat the system.