SAN FRANCISCO -- U.S. shot put champion Kevin Toth is among the dozens of Olympic and professional athletes subpoenaed by a federal grand jury probing a Bay Area lab that prescribes nutritional supplements, Toth's lawyer said Saturday.

The grand jury is expected to begin its probe this week into the Bay Area Laboratory Co-Operative, which was raided in early September by agents of the Internal Revenue Service and a San Mateo County narcotics task force.

The focus of the grand jury is unclear. Federal officials have refused to discuss whether a grand jury has been formed to look into the BALCO case.

Toth, who placed fourth at the world championships this summer after winning his first national title in late June at the U.S. championships at Stanford, may testify as early as this week.

"He's one of the people that's been subpoenaed. He's honoring the subpoena, he'll do whatever he's supposed to do," Toth's agent, John Nubani, said in a telephone interview from his Pittsburgh home.

Nubani said Toth has used BALCO products, including the zinc-magnesium supplement ZMA. But Nubani also stressed that the 35-year-old Toth, of Hudson, Ohio, never has been suspended for a drug violation during his career.

"Most athletes on the tour take multiple, multiple amounts of vitamins," Nubani said. "He's never tested positive. He's one of those guys that's always been there, always done what he was supposed to do."

Victor Conte, founder of Burlingame-based BALCO, said in an e-mail Friday to The Associated Press he was told by athletes that 40 of them have been called to testify before the grand jury starting next week.

Conte said he has not been subpoenaed. Sprinter Kelli White, who has been associated with BALCO and has tested positive for a banned substance, told the San Francisco Chronicle she had received a grand jury subpoena.

In addition to being raided last month, an anonymous coach who turned in a used syringe containing a designer steroid to the U.S. Anti-Doping Agency said he got the substance from Conte. The steroid turned out to be tetrahydrogestrinone, or THG.

Until recently, THG was undetectable in doping tests. After analyzing the substance and adjusting its tests, USADA retested the samples of hundreds of track athletes and said several had tested positive for THG at the U.S. championships at Stanford -- a violation that could lead to a two-year suspension.

Major league baseball will be unable to retest samples taken this year for THG, but plans to discuss with players whether to add it to the list of banned substances.

Conte has said he was not the source of the substance.

BALCO analyzes blood and urine from athletes, then prescribes a regimen of supplements to compensate for various vitamin and mineral deficiencies. Among its clients are top track stars, as well as baseball's Barry Bonds and the NFL's Bill Romanowski.