Barry Bonds (search) on Thursday became the highest-profile athlete to appear before a grand jury focusing on possible tax and drug violations by a lab that supplied nutritional supplements to Bonds and other sports stars.

The six-time National League MVP entered the grand jury room late Thursday morning accompanied by attorney Mike Rains. Bonds left the room nearly 5 hours later, though it was unclear how long he testified.

"It went fine," Bonds said as two bodyguards and two federal marshals led him to a freight elevator. He was taken to the garage of the federal courthouse, then driven away as a marshal stopped traffic.

Benito Santiago, a free agent who spent the past three seasons as Bonds' teammate with the San Francisco Giants, testified for 45 minutes later in the afternoon.

Other athletes who already have appeared before the grand jury include track star Marion Jones and her boyfriend, 100-meter world record-holder Tim Montgomery, four Oakland Raiders and Olympic champion swimmer Amy Van Dyken.

An appearance before the grand jury, or being subpoenaed to testify, does not mean an athlete is a target of the probe.

Two people have been named so far as targets of the grand jury -- Victor Conte, founder of the Bay Area Laboratory Co-Operative (search), or BALCO, and Greg Anderson, Bonds' personal trainer.

The grand jury is focusing on possible tax and drug violations by BALCO. Anderson's home was raided by the Internal Revenue Service and a drug task force Sept. 5, two days after a similar raid at BALCO.

BALCO also is at the center of an investigation by anti-doping agencies into the newly discovered designer steroid THG (search).

Conte denies supplying athletes with THG, and Bonds repeatedly has denied using steroids.

Bonds has attributed his muscular development over the years to intense weight training, proper diet and a regimen of nutritional supplements (search) from companies such as BALCO.

Bonds, 39, became a BALCO client just before the 2001 season, in which he hit a record-setting 73 homers. He has praised Conte for giving him a personalized nutrition program.

Bonds posed with Conte and Anderson for this past June's issue of Muscle & Fitness magazine and heaped praise on both.

"I visit BALCO every three to six months. They check my blood to make sure my levels are where they should be. Maybe I need to eat more broccoli than I normally do. Maybe my zinc and magnesium intakes need to increase," Bonds told the magazine.

"Victor will call me to make sure I'm taking my supplements, and my trainer Greg will sit near my locker and stare at me if I don't begin working out right away. I have these guys pushing me."

Bonds brought Anderson, a childhood friend, on a major league tour of Japan after the 2002 season, when the trainer met players such as Jason Giambi -- who also has been subpoenaed to testify before the grand jury.