NEW YORK - Baseball launched its probe Thursday into alleged steroids use by Barry Bonds and others, and right away the head of the investigation came under attack because of his close ties to the sport.

In the wake of a searing book about Bonds, commissioner Bud Selig appointed former Senate Majority Leader George Mitchell — and currently a director of the Boston Red Sox — to lead the inquiry.

The probe initially will be limited to events since September 2002, when the sport banned performance-enhancing drugs, but Mitchell has the authority to expand it. Selig said Mitchell’s report will be made public but didn’t set a timetable.

“The goal here is to determine facts, not engage in supposition, speculation, rumor or innuendo,” Selig said.

Whatever the findings, it will be hard to penalize anyone for conduct before the steroids ban. Baseball began drug testing in 2003 and started testing with penalties the following year.

At San Francisco’s home ballpark, Bonds wouldn’t discuss the matter.

“I said no, no, no,” he said, shaking his head. “I’m going to jump off the Empire State Building — flat on my face,” he added, laughing.

Mitchell, meanwhile, said he will not resign his position with the Red Sox. He also is chairman of The Walt Disney Co., the parent of ESPN, a national broadcast partner of baseball.

“I don’t think there’s any conflict,” he said in a telephone interview with The Associated Press. “I’m going to be independent, have complete independent authority and will act.”

ESPN is airing a weekly behind-the-scenes look at Bonds — with the San Francisco star’s cooperation — starting next week.

Along with working for the Red Sox, Mitchell is a former director of the Florida Marlins and served on an economic study committee Selig appointed in 1999. He said he previously announced he would leave the Disney board by the end of the year.

“I’ve assured the Red Sox owners that should any matter arise, anybody affiliated with the Red Sox will be treated exactly as will anyone else,” he said.

John Dowd, the Washington lawyer who headed baseball’s investigation of Pete Rose’s gambling in 1989, did not like the choice.

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“Mitchell doesn’t have a great track record with me. It doesn’t look like he’s independent,” Dowd said.

Sen. Jim Bunning, a Kentucky Republican and baseball Hall of Famer, also criticized Mitchell.

“While George Mitchell is certainly a man of great integrity, I believe that baseball would have been wiser to pick someone who is not as close to the game and may be able to take a more objective look into the facts,” Bunning said.

Rep. Henry Waxman, a California Democrat who helped lead a congressional hearing last year on steroids in baseball, praised the probe.

“This is precisely what I had asked MLB to do last year,” he said. “Finding out the truth about the depth and breadth of this problem is the only way to close the book on this sad chapter of the game’s history.”

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Selig’s decision came soon after “Game of Shadows,” a book by two San Francisco Chronicle reporters detailing alleged extensive steroid use by Bonds and other baseball stars.

“I believe the timing on this proper given the charges, given the specificity of the charges for the first time,” Selig said.

Mitchell will be assisted by Jeffrey Collins and Thomas Carlucci of Foley & Lardner — the law firm of Bob DuPuy, baseball’s chief operating officer — and Charles Scheeler, a former federal prosecutor currently at Mitchell’s law firm, DLA Piper Rudnick Gray Cary. Collins is a former U.S. Attorney and Carlucci a former assistant U.S. attorney.