FBI agents on Monday searched the home of the woman at the center of the sex scandal that led to the resignation of CIA director David Petraeus after new revelations surface about the affair.
Defense Secretary Leon Panetta, himself a former CIA chief, said Petraeus had been right to resign as a matter of "personal integrity", while Washington struggled to digest a steady stream of leaked allegations.
Petraeus resigned on Friday, just three days after Obama was re-elected president following a heated campaign in which the CIA faced questions about its handling of a deadly attack on a US consulate in Libya.
The retired four-star general had been due to testify to Congress this week on the September 11 assault in Benghazi that killed four Americans, including US ambassador Chris Stevens and two former Navy SEALs working for the CIA.
Panetta, Petraeus's predecessor and the most senior administration figure to yet speak out on the resignation, attempted to draw a line under the scandal.
"My heart obviously goes out to him and his family. But I think he took the right step," he told reporters aboard a flight to Australia.
"I think it's important when you're director of the CIA, with all of the challenges that face you in that position, that personal integrity comes first and foremost."
Retired US Army colonel Steve Boylan -- a close Petraeus associate -- told AFP he "regrets the poor judgment and the lack of discipline more than we can probably put into words ... His words to me were 'I screwed up.'"
Boylan, who served as Petraeus's spokesman when the pair were in Iraq, said the 60-year-old Petraeus had warned his wife of 38 years, Holly, about his affair before the news broke and was trying to make amends.
Boylan said the affair between Petraeus and his biographer Paula Broadwell began about two months after he assumed his post at the CIA in September 2011, and thus after he retired from the US Army. It ended about four months ago.
It all unraveled when 37-year-old Jill Kelley, a Tampa socialite with close military ties who was a friend of the Petraeuses, complained to an FBI agent acquaintance that she had received threatening anonymous emails.
According to widely-reported leaks from US officials, FBI agents traced the mails back to Broadwell and, on scrutinizing her online records, found a series of sexually explicit exchanges with Petraeus confirming their affair.
The pair was interviewed separately by investigators in late October and early November but, despite reports Broadwell was found to be in possession of some classified material, no criminal charges were brought.
Nearly a dozen FBI agents on Monday searched Broadwell's North Carolina home, removing bags, boxes and pictures, local media reported. She has not been seen at her home since Petraeus resigned over the affair.
Broadwell may have revealed classified information last month by claiming at a public forum that the CIA was detaining Libyan militia members and that the practice may have triggered the September 11 attack on the US consulate.
The spy agency has strongly denied holding prisoners at the CIA annex in Benghazi.
Petraeus took command of the CIA 14 months ago, retiring from the military after a glittering career that saw him lead the 101st Airborne, the US war in Iraq, its CentCom regional command and international forces in Afghanistan.
Two months after hanging up his uniform, according to Boylan, he started an affair with Broadwell, a former army officer 20 years his junior who traveled with him in Afghanistan and has written a glowing biography of him.
Adding political intrigue to the scandal -- according to a report in Tuesday's Wall Street Journal -- the original FBI agent who was contacted by Kelley brought the matter to the attention of Republican lawmakers.
They in turn contacted the FBI, and Petraeus resigned late last week.
Meanwhile, the FBI investigation itself has come under scrutiny.
According to the Wall Street Journal, supervisors pulled the whistleblower FBI agent off the case after he became "obsessed" with the matter and was caught sending Kelley shirtless photos of himself.
US lawmakers already plan hearings into the Benghazi debacle and claims the four US victims were denied sufficient protection because of confusion between CIA and State Department leaders over security responsibility.
Now they also want to know why the FBI and Justice Department did not inform them or the White House about Petraeus's affair until last week, after the spy chief's sudden departure and public admission of guilt.
The scandal has also left Obama with a hole to fill on his national security team at a time when he is also expected to be replacing his secretaries of state, defense and treasury.
One name being floated as a possible Petraeus replacement is John Brennan, the White House counter-terrorism adviser and a CIA veteran. Others say Michael Morell, the agency's acting director, may take on the role.