San Francisco ? Barry Bonds’ personal trainer again refused to testify before a grand jury investigating the Giants slugger Thursday, but a federal judge did not jail Greg Anderson for contempt of court.

U.S. District Judge William Alsup said he must review the transcript of the brief grand jury hearing and hear arguments from lawyers before deciding if Anderson should go back to jail. He ordered Anderson to return to court Aug. 28.

On Anderson’s fifth appearance before a federal grand jury, he answered basic questions, including his name, prosecutors said. Until now, he didn’t even go that far.

But federal prosecutors said Anderson didn’t answer any substantive questions about steroids and that his answers were designed to delay the process, Assistant U.S. Attorney Matthew Parrella argued.

“This was a more cynical appearance than any before,” Parrella said.

For instance, Anderson refused to answer when Parrella asked, “Did you distribute anabolic steroids to Barry Bonds?”

That was the first public acknowledgment that Bonds, second on major league baseball’s all-time home run list, is the target of a grand jury investigation into a performance-enhancing drug probe linked to some of the world’s top athletes, including Yankees slugger Jason Giambi and sprinter Tim Montgomery.

All other reports have been based on leaked copies of grand jury transcripts in the investigation of the Bay Area Laboratory Co-Operative that netted five convictions for steroid distribution. Several elite athletes testified about their steroid use and Parrella told the judge the new investigation involved whether “some of those athletes committed perjury and/or obstructed justice.”

Parrella said prosecutors wanted Anderson to explain calendars with doping schedules and other evidence seized from his house.