CBS turned to a former attorney general and a retired wire service executive yesterday to lead an independent probe of how it botched the story on President Bush's National Guard service that produced an apology this week.

Richard Thornburgh, who ran the Justice Department during parts of the Reagan and George H.W. Bush administrations, will conduct the investigation with Louis D. Boccardi, who retired as chief executive of the Associated Press. Thornburgh is also a former Republican governor of Pennsylvania.

CBS President Les Moonves and news division chief Andrew Heyward picked the pair in an effort to begin repairing the damage from the "60 Minutes" report on Bush based on documents that the network now acknowledges it cannot authenticate.

"It's a journalistic challenge to look at the handling of the story, what was done, what was not done and see what lessons we can derive for CBS News," Boccardi said. "I spent four decades of my life wrestling with journalistic issues. . . . I know it's a hornet's nest, but I feel I can make a contribution." He said CBS has assured him of full cooperation and that the report will be made public.

Alex S. Jones, director of Harvard's Shorenstein media center, called Boccardi "as honorable a man as I know in the media business." But once the panel issues its report, Jones said, "there has to be a demonstration that CBS is going to be doing things differently."

The Justice Department tapped Thornburgh in 2002 to examine the collapse of WorldCom Inc. Former federal prosecutor Victoria Toensing said Thornburgh is a good choice for CBS "because he's a Republican, so it doesn't look partisan the wrong way."

But some CBS staffers questioned the selection of a man once named to the Cabinet by the father of the story's subject, and they asked why Heyward, who approved the "60 Minutes" story, was involved in the appointments. "I don't see it as a hanging crime, but it would have been better to let someone not involved make those appointments," said Tobe Berkovitz, an associate communications dean at Boston University.

There are signs that the controversy is hurting CBS and anchor Dan Rather at the local level. Bob Lee, general manager of WBDJ-TV in Roanoke and president of the CBS Affiliates Association, said he has heard from many stations and "we're all being battered."

"There is a body of people who just intensely dislike Dan Rather and see an opportunity to demand his immediate resignation, or that he be shot," Lee said. A smaller group, he said, view the reaction as "the Republican right wing just trying to drum Dan out of the business. Viewers have been quite vocal that while they admire, respect and trust our local news organization, we are so tarnished by this lapse of judgment at the network that they may take their viewing elsewhere."

WNIS-AM in Norfolk said yesterday that it is dropping its agreement to carry CBS News reports after 12 years and switching to ABC because of the Guard story. "Our listeners have clamored for a change," said spokesman Dave Morgan, adding that CBS's credibility has been "seriously damaged by the ongoing scandal."

CBS spokesman Dana McClintock expressed "regret" that WNIS "made this decision based on this one issue alone." He said CBS affiliates and viewers "deserve a better explanation of how this came to pass" and expects the new panel to provide one.

Louis Boccardi, left, and Richard Thornburgh will investigate how the memos came to be on "60 Minutes."