SAN FRANCISCO — They aren’t through with Barry Bonds, not yet.

The federal grand jury considering possible perjury and tax-evasion charges against the star slugger expired yesterday without an indictment. Hours later, Bonds’s personal trainer, Greg Anderson, walked out of a prison where he spent two weeks for refusing to testify against his childhood friend.

“We are not finished,” U.S. Attorney Kevin Ryan said. “We have postponed the decision (to indict) for another day in light of some recent developments.”

Though prosecutors wouldn’t confirm the existence of a new grand jury, Anderson’s lawyer, Mark Geragos, said there was one.

He said his client has been subpoenaed to testify before a new panel that will take up the question of whether Bonds lied under oath when he said he never knowingly took performance-enhancing drugs.

“They can subpoena him every day for the rest of this year, and it doesn’t matter,” Geragos said. “He’s not going to talk.”

Giants owner Peter Magowan said he hoped to see a resolution soon.

“I think all of us would like to see a resolution, I mean everybody in baseball,” Magowan said. “I’m sure the commissioner would like to see one, I’m sure Barry would like to see one, and I’m sure the fans would like to see one.”

Speculation has been mounting for weeks that Bonds, one of the biggest names in professional sports, would be indicted yesterday with the grand jury expiring. His lawyers had said they were preparing a defense.

But soon after the grand jury reported to the federal courthouse for the final day of its probe, the U.S. Attorney’s office issued a statement saying it “is not seeking an indictment in connection with the ongoing steroids-related investigation.”

“They don’t even have enough to indict a ham sandwich, let alone Barry Bonds,” the slugger’s lawyer, Michael Rains, said.

Joseph Russienello, the U.S. Attorney in San Francisco from 1982 to 1990, said handing the case off to a new grand jury means the federal government can lock up Anderson for the length of the new grand jury’s term, which could extend beyond a year.

“It’s no longer a two-week vacation,” Russienello said. “Twelve months usually has a way of getting people sensitized to giving truthful testimony.”

Rains said there was “temporary relief in the news we heard today.” But he seemed to back away slightly from Bonds’s earlier statements that he didn’t know the substances given to him by Anderson were steroids.

“He was suspicious in light of what he had read as to whether those were steroids or not,” Rains told reporters outside the federal courthouse.

Anderson appears to be the key to whether perjury charges could stick against Bonds.

“We will continue to move forward actively in this investigation — including continuing to seek the truthful testimony of witnesses whose testimony the grand jury is entitled to hear,” said Luke Macaulay, a spokesman for Ryan.

Bonds testified in 2003 that he thought substances given to him by Anderson were arthritis balm and flaxseed oil. Authorities suspected Bonds was lying and that those items were “the clear” and “the cream” — two performance-enhancing drugs tied to the Bay Area Laboratory Co-Operative, the lab exposed as a steroids supplier to top athletes in a variety of sports.