SAN FRANCISCO -- A former bass player once known as "Walkin' Fish," who left the music world to start a nutritional supplements lab, is no longer playing a backup role. He's now in the spotlight as the focus of a drug probe involving some of the nation's top sports stars.

Victor Conte played with groups such as Tower of Power in the 1970s. He worked with jazz pianist Herbie Hancock in 1980. Then he moved to a different stage, creating supplements that quickly became popular with stars in sports ranging from baseball to football to track.

Conte's lab was raided by the Internal Revenue Service and a team of drug agents in early September, and he's now the target of a federal grand jury probe. He's also accused of supplying athletes with a new designer steroid that is rocking the world of track and field.

New York Yankees first baseman Jason Giambi became the latest athlete to acknowledge he has been subpoenaed to testify before the grand jury. Sprinter Kelli White and shot putter Kevin Toth have also said they received subpoenas.

"I didn't do anything wrong," Giambi said Monday at a World Series workout in Miami. "To be honest with you, I really don't know much about it. I really don't know what it's about."

An attorney for Barry Bonds told the San Francisco Chronicle that Bonds was also subpoenaed and will testify Dec. 4. The home of Bonds' personal trainer, Greg Anderson, was raided last month in conjunction with the raid on Conte's lab.

"They have verbally told me that Barry is not a target," lawyer Michael Rains said. "I called and invited the prosecuting attorney to sit down with me and possibly even with Barry at some date before his appearance to see if we could hash out what it is they need to know and whether or not Barry has any useful information."

Conte, who runs the Burlingame-based Bay Area Co-Operative Laboratory, or BALCO, has said in e-mails that athletes have told him that 40 Olympic and professional athletes have been subpoenaed.

Federal officials have refused to discuss whether a grand jury is looking into Conte or BALCO. The scope of the probe is unclear. Being subpoenaed does not imply that any of the athletes has done anything wrong.

"My client is innocent until proven guilty," Conte's attorney, Robert Holley, said Monday in a telephone interview. "So far as I know, he is the target of the investigation."

In addition to being the subject of the federal probe, Conte was named by an anonymous track coach as the source of a substance that turned out to be a previously undetectable steroid, tetrahydrogestrinone, or THG. Conte has denied he was the source.

The U.S. Anti-Doping Agency said last week it had retested hundreds of samples from track and field athletes after identifying THG, and that several had tested positive during the U.S. track championships at Stanford in late June. They now face two-year suspensions for using a banned substance.

On Tuesday, track and field's world governing body said it will retest drug samples from the World Championships held near Paris in August to search for THG. The International Association of Athletics Federations said it has about 400 urine samples from that meet. Any positive findings would lead to retroactive disqualifications, including stripping of any medals, and two-year bans.

On Monday, NFL spokesman Greg Aiello said the league may retest its samples for the presence of THG. Steroid use is banned by the NFL, and violators are subject to suspension.

"It's a possibility," Aiello said. "We are not ruling it out."

Major League Baseball said Saturday it 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 worked as a bass player from 1965 to 1983, collaborating on 15 albums. One of the bands in which he played was called Pure Food and Drug Act -- perhaps an ironic foreshadowing of his future career.

He and a cousin, guitarist Bruce Conte, started a band called Common Ground and then moved to the soul group Tower of Power from 1977 to 1979. Victor Conte played on one album with the group, the 1978 release "We Came to Play."

The Conte cousins started a band called Jump Street in 1979, and Victor moved on to that gig with Hancock. He was called "Walkin' Fish" by fellow musicians "for reasons obvious to those who have had the pleasure of seeing him onstage," one guitarist said.

Then he left the music world in the early 1980s to start BALCO, which analyzes blood and urine from athletes and then prescribes a regimen of supplements to compensate for vitamin and mineral deficiencies.

Among its clients are top track stars, as well as baseball's Barry Bonds and the NFL's Bill Romanowski. Bonds has been a BALCO client since the winter of 2000. In the June issue of Muscle & Fitness magazine, he credited Conte for a personalized program that includes nutritional supplements.

This is not the first time Conte has been at the center of a drug case.

When four separate tests before the 2000 Sydney Olympics showed U.S. shot putter C.J. Hunter had 1,000 times the allowable amount of the steroid nandrolone in his system, Conte took the blame, claiming the positive tests were the result of contaminated iron supplements he had supplied to Hunter.

Conte said Hunter, the former husband of Olympic sprint champion Marion Jones, took the same supplement used by sprinters Linford Christie and Merlene Ottey -- both of whom were suspended by world track officials after testing positive for nandrolone.

And a doctor with a long association with BALCO was the one who supplied sprinter Kelli White with the stimulant modafinil, which White says she took for the sleep disorder narcolepsy.

White tested positive for modafinil this summer at the World Championships, putting her gold medals in the 100 and 200 meters at risk.