The CIA has launched an internal inquiry following the resignation of its director David Petraeus, who confessed to an extramarital affair, a spokesman for the US intelligence agency said Thursday.
"If there are lessons to be learned from this case, we'll use them to improve," said the spokesman, Preston Golson.
"But we're not getting ahead of ourselves. An investigation is exploratory and doesn't presuppose any particular outcome," he added.
Petraeus, who was already the most celebrated US general of his generation before he took the helm at the CIA last year, resigned last week to pre-empt the revelation that he had had an affair with his biographer.
The scandal sent shockwaves through the Washington security establishment and entangled the US commander of allied forces in Afghanistan, General John Allen, whose career is on hold pending a Pentagon investigation.
Petraeus has kept a low profile since his resignation, but he will be in the limelight once again on Friday when he heads to Capitol Hill to testify before two congressional committees over a deadly attack on a US mission in Libya.
The 60-year-old retired general is not expected to face charges, but FBI agents seized a trove of documents from the home of his mistress, 40-year-old Paula Broadwell, and may act if she improperly received classified material.
US Attorney General Eric Holder said Thursday that the FBI had not found any "national security threat" in the course of its investigation.
Petraeus' resignation also triggered speculation that its timing -- three days after President Barack Obama's re-election -- was political or was linked to the probe into the killing of four Americans at the Benghazi consulate.
Lawmakers are still demanding answers, with Senator Chuck Grassley -- the senior Republican on the Senate Judiciary Committee, which has oversight of the FBI -- asking Holder and FBI director Robert Mueller for a timeline of events.
"A number of questions have been raised about the FBI's actions during the course of its investigation of the Petraeus matter," Grassley said.
"It would be best for the administration to be forthright and transparent so the country can feel comfortable that our chief domestic law enforcement agency is doing everything properly under the law to protect national security."
Petraeus has yet to speak publicly, but he told a friend, CNN Headline News anchor Kyra Phillips, that the scandal had nothing to do with Benghazi and that he had never passed secret documents to his lover.
"He was very clear that he screwed up terribly -- it was all his fault -- even that he felt fortunate to have a wife who is far better than he deserves," Phillips said, after a series of calls to Petraeus.
"He has insisted to me that he has never passed classified information to Paula Broadwell," she added. "He has said this has nothing to do with Benghazi and he wants to testify. He will testify."
Petraeus will face both the House and Senate intelligence committees on Friday as they probe the September 11 attack on the consulate in Benghazi, in which Ambassador Chris Stevens and three more Americans died.
Two of the dead were former Navy SEALs working as paramilitary agents for Petraeus' CIA, and questions have been raised about whether the agency or the State Department was responsible for security at the exposed outpost.
Broadwell herself further muddied the waters by suggesting in a public speech that the CIA team in Benghazi was holding local prisoners and that this was what inspired Islamist militants to launch their assault.
The CIA has firmly denied her claim, made before the scandal broke.
Petraeus met Broadwell in 2006 when she was studying for a doctorate at Harvard. They hit it off and she was invited to follow him to Afghanistan to study his command for what was to become a fawning biography.
The four-star general retired from the military last year and took over at the CIA. Shortly afterwards, according to Petraeus' friends, he and Broadwell became lovers, and remained so until they split around four months ago.
The affair came to light as a result of an FBI inquiry that was launched in May when Jill Kelley, a 37-year-old Tampa socialite who hosted parties for officers at US Central Command in Florida, complained of threatening emails.
Agents traced the anonymous emails to Broadwell's computer and found that she had been jealous of Kelley's rapport with both Petraeus and Allen.
While investigating cyberstalking they uncovered sexually explicit emails between Petraeus and Broadwell. The investigation might have remained secret, but an FBI agent raised concerns with a congressman and the scandal broke.
This week, Allen was pulled into the drama, when it was revealed he had written hundreds of emails to Kelley, some of them reportedly "flirtatious," and the Pentagon launched an inquiry into his conduct.
He was expected to be promoted to become NATO's Supreme Allied Commander, but Obama has put this on hold until the result of the investigation.