Evidence points to no security risk in Petraeus affair By Mark Hosenball and Andy Sullivan WASHINGTON (Reuters) - Classified material kept by the woman who conducted an affair with former CIA Director David Petraeus predates their liaison and does not come from the spy agency, sources briefed on the investigation told Reuters on Thursday. The finding appears to bolster assertions by both Petraeus and his biographer, Paula Broadwell, that their affair did not put national security secrets at risk - a central question hovering over the scandal that brought down one of the United States' most respected public figures last week. The CIA said on Thursday it had opened an "exploratory" investigation into Petraeus' conduct, building on the FBI's probe. Law enforcement officials have said they believe the FBI investigation is likely to end without criminal charges. The scandal has cast a spotlight on the private lives of some of the nation's top national security officials. The commander of U.S. and NATO forces in Afghanistan, Marine General John Allen, now faces a Pentagon inspector general's review of what sources describe as "flirtatious" emails with a Tampa socialite. Defense Secretary Leon Panetta ordered the military's top brass to look for any gaps in ethics amid concerns officers' lapses in judgment could erode public confidence in the military. Traveling in Bangkok, Panetta said he knew of no other military officials who have been drawn into the investigation. Petraeus and Broadwell have separately told investigators they did not share security secrets, and Petraeus has repeated that assertion to associates and a television reporter. In his first public comments on the matter, Attorney General Eric Holder said on Thursday the FBI did not see any possible threats over the course of the investigation that were urgent enough to notify President Barack Obama or lawmakers until shortly before Petraeus stepped down. FBI agents have found a substantial amount of classified information on Broadwell's personal computer since they searched her Charlotte, North Carolina, home with her consent on Monday. Sources briefed on the investigation said the documents date from before August 2011, when Petraeus took up his post at the CIA and the two started their affair. None of the material comes from the CIA. However, she would still have to comply with strict rules that lay out how sensitive materials must be protected. Broadwell's security clearance has now been suspended. She could have it revoked and face harsher penalties if it is found she mishandled classified data. Petraeus' remarks notwithstanding, investigators said on Thursday they had not ruled out the possibility that he passed on classified material to Broadwell. Some lawmakers have questioned why they were not notified of the probe until after last week's presidential election. Holder, at a news conference in New Orleans, defended the Justice Department's handling of the case and its sharing of information with top Obama administration officials. "After a pretty critical interview occurred the Friday before we made that disclosure, when we got to that point where we thought it was appropriate to share the information, we did so," Holder said at a news conference. Petraeus is due on Friday to face lawmakers who are examining the September attacks in Benghazi, Libya, which led to the death of four Americans, including the U.S. ambassador. The questioning will be confined to the events in Benghazi, said one lawmaker who is expected to participate. "We'll get his perspective on what information he knew and how his assessment of that intelligence changed over time," said Democratic Representative Adam Schiff. Petraeus told the television network HLN that he resigned because of the affair, not Benghazi. Additional reporting by Phil Stewart in Bangkok, Rick Rothacker in North Carolina, Kathy Finn in New Orleans and Tabassum Zakaria, Susan Cornwell and David Ingram in Washington; Editing by Warren Strobel and Todd Eastham