SAN FRANCISCO — The federal agent who spent a late summer afternoon tracking a Chevy Tahoe with license plate "W8 GURU" followed it first to a nutritional supplements lab and then to a baseball park.

Newly released federal documents claim the driver of that vehicle was Barry Bonds' personal trainer, Greg Anderson, one of four men charged last week in a steroid-distribution ring that allegedly supplied dozens of professional athletes with banned substances.

The documents released Tuesday say a federal agent followed Anderson on Sept. 11, 2002, as he made a quick visit to the Bay Area Laboratory Co-Operative — the lab allegedly at the center of the steroid ring.

"Anderson returned to his vehicle and proceeded to drive directly, without stopping, to Pacific Bell Park, a professional baseball stadium," the documents say. "Anderson was followed until he entered the players' parking lot area of the professional baseball stadium, past a gate and guarded entrance." The San Francisco Giants played a home game at Pac Bell Park against the Los Angeles Dodgers on Sept. 11, 2002. Bonds went 2-for-4 with an RBI double, but the Giants lost 7-3.

According to the documents released Tuesday, Anderson told federal agents he gave steroids to several professional baseball players. It was unclear whether Anderson provided specific names to the federal agents.

No players were identified in the documents released at a news conference at the U.S. attorney's office in San Francisco, and the only time a player's name was used in the 24 pages of documents it was blacked out.

But at least two newspapers around the country were e-mailed versions of the documents, and that player's name mistakenly was not blacked out. The New York Times and Milwaukee Journal Sentinel reported that Gary Sheffield was listed as having sent a package to BALCO on Feb. 17, 2003. Sheffield, who signed with the New York Yankees as a free agent in December after two seasons with the Atlanta Braves, was one of several baseball players who testified before the grand jury in the BALCO case.

The material inadvertently sent to the newspapers does not allege that Sheffield used steroids and does not specify what was in the package.

Sheffield said Wednesday he was surprised to see his name mentioned in connection with BALCO.

"Yeah, of course, but I have no comment otherwise. There is nothing I need to worry about," he said at the Yankees' spring training camp in Tampa, Fla.

Anderson and the three other men charged last week have pleaded innocent. No athletes have been charged.

Federal officials released two affidavits Tuesday that supported search warrants used in raids on Anderson's home in September.

"Inside Anderson's residence, agents found steroids, syringes and other paraphernalia associated with steroid distribution activities," the documents say. "In addition, agents found files identifying specific athletes. These files contained calendars, which appear to contain references to daily doses of steroids and growth hormones."

The indictment announced last week said federal agents found about $63,920 in cash in a locked safe at Anderson's residence during the first raid.

"Some of the money was broken up into separate envelopes with the first names of known athlete clients written on them," the documents released Tuesday say.

The new documents say Anderson initially denied distributing steroids in discussions with federal agents but later said he sometimes "gave" steroids to people he knew.

"Upon further questioning, Anderson admitted that he had given steroids to several professional baseball players," the documents say.

Anderson was not immediately available for comment. A spokeswoman for Bonds said he wouldn't have any comment Tuesday.

The newly released documents also say BALCO founder Victor Conte admitted giving steroids to Anderson.

"Conte acknowledged that he knew Greg Anderson and stated that he gave Greg Anderson steroids to give to professional baseball players," the documents say. "Conte stated that he knew it was illegal to do this and that he 'assumed' Anderson knew it was illegal."

Conte and his attorneys were not immediately available for comment.