The FBI and prosecutors in Florida and North Carolina began investigating the possibility of email hacking, because at least some of the emails sent by Ms. Broadwell to the other woman included contents of messages that appeared to come from Mr. Petraeus’s own account, these people said. The Justice Department and high-level officials, including Attorney General Eric Holder, were aware of the investigation for months, having to approve certain parts of the investigation.

Over the course of the probe, prosecutors realized there wasn’t a cyber-breach. Instead, Mr. Petraeus had shared some access to the account with Ms. Broadwell, possibly to exchange messages, these people said.

After examining Ms. Broadwell’s emails, they instead began investigating the possibility that Mr. Petraeus had shared classified information with Ms. Broadwell, which proved not to be the case, these people said.

House Majority Leader Eric Cantor (R-Va.) says he was told in late October about allegations that then-CIA Director David Petraeus was having an extramarital affair…

“I was contacted by an F.B.I. employee concerned that sensitive, classified information may have been compromised and made certain [FBI] Director [Robert] Mueller was aware of these serious allegations and the potential risk to our national security,” said Cantor in a statement to the Times.

The report says Cantor spoke to the FBI employee after being told by Rep. Dave Reichert (R-Wash.) that someone at the agency had concerns about national security and wanted to speak to a congressional leader about the allegations.

A senior intelligence official said Saturday that Mr. Clapper had learned of Mr. Petraeus’s situation only when the F.B.I. notified him, about 5 p.m. on Tuesday, election night…

If the investigation had uncovered serious security breaches or other grave problems, [a government official] said, the notifications would have been immediate. As it was, however, the matter seemed to involve private relationships with little implication for national security…

White House officials said they were informed on Wednesday night that Mr. Petraeus was considering resigning because of an extramarital affair. On Thursday morning, just before a staff meeting at the White House, President Obama was told.

The White House says no one there knew about the Petraeus situation before Wednesday and the president himself was informed Thursday. But if the story had broken a week earlier, those headlines would have overtaken much of the president’s message about the middle class and his work in the aftermath of Hurricane Sandy. Who made the decision to wait, and why, is going to be the subject of scrutiny as this scandal continues to unfold…

Petraeus appears to have successfully kept the situation quiet for months, if not longer. He had known for all that time that he was violating the moral and professional code that he cited in his message to CIA employees Friday. And he knew for weeks that the FBI was looking into the situation.

But something made him come forward now.

Gen. David Petraeus told friends his affair with his biographer, Paula Broadwell, began after the four-star general left the army in August 2011, sources told ABC News.

Petraeus is said to have been the one to have broken off the extramarital affair…

Investigators uncovered no compromising of classified information or criminal activity, sources familiar with the probe said, adding that all that was found was a lot of “human drama.”

CIA officers long had expressed concern about Broadwell’s unprecedented access to the director. She frequently visited the spy agency’s headquarters in Langley, Va., to meet Petraeus in his office, accompanied him on morning runs around the CIA grounds and often attended public functions as his guest, according to two former intelligence officials.

Petraeus’ staff when he was overseeing the war in Afghanistan similarly had been concerned about the time she spent with their boss.

News of the affair did not come as a total surprise—not to those who saw Petraeus and “the woman in the case,” Paula Broadwell, together in Kabul during Petraeus’s final year in command there through July 2011. Broadwell had been working for some time on a biography of Petraeus. He had agreed to aid her project: giving long interviews, allowing his staff to talk to her, clearing the path to colleagues and mentors from earlier in his career. By that last year in Kabul, it was clear to all who saw them that the pair had established a close relationship…

Petraeus’s staff-group in Kabul was intensely loyal to him. Some had been with him virtually since the invasion of Iraq in 2003. They knew that Petraeus had been deployed for three-fourths of the time since then. By this final tour, he was close to exhaustion. If Broadwell’s company—and transparent admiration— eased Petraeus’s burdens, so be it. When an inquiring reporter asked about Broadwell, late of an evening, a raised eyebrow and a shrug were as far as one staff-officer would go. One of Petraeus’ mentors, a retired army general, did allow that he had cautioned Petraeus. He was sure nothing was out of line, he hastened to say, but “appearances matter.”

“I found her relationship with him to be disconcerting,” said a former aide to Petraeus, one of several who insisted on anonymity in order to speak candidly about his former boss. “Those who worked for him never tried to leverage our relationship with him. It seemed to a lot of us that she didn’t have that filter.”…

“She was relentlessly pro-Petraeus,” said a longtime Afghan policy expert who met Broadwell in Kabul. “There was no room for a conversation of shortcomings of the Petraeus theology. She wasn’t a reporter. She struck me as an acolyte.”…

Officers close to Petraeus grew concerned about her posts on Facebook, which they believed sometimes divulged sensitive operational details. The posts, intended for friends back home, were often playfully written and aimed at showing off her adventures in the war zone.

As a military expert with ties around the world, Paula Broadwell kept a busy schedule packed with writing, teaching and helping wounded soldiers, leaving little time for the married mother to commit “indiscretions,” a friend told ABC News.

“I have some serious questions about who is connecting these dots and how. … Paula Broadwell is not the type … she isn’t,” said David Bixler, an active duty double amputee who met Broadwell though a charity foundation in 2010…

People close to Petraeus told ABC News they found Broadwell too “gushy” about the general, whom she viewed as a mentor, and commented to each other that they believed the 40-year-old was “in love with him.”

Though Petraeus is not expected to testify at the committee’s closed-door hearing [at Benghazi] next week, Chambliss said on ABC’s This Week that Petraeus’s testimony will likely happen later. “He’s trying to put his life back together right now and that’s what he needs to focus on,” Chambliss said.

Speaking on Fox News Sunday, Senator Dianne Feinstein, the California Democrat who chairs the committee, also said Petraeus would likely testify eventually.

Speaking on CBS’s Face the Nation, Sen. Lindsey Graham, R-S.C., who has been among Republican senators loudly urging hearings on Benghazi, called it “absolutely essential.”

“I don’t know (the) exact date of when all of this process began and what took place there, but we’re — we’re confident that David Petraeus was very straight up with us during the confirmation hearings,” said Chambliss, the vice chair of the Senate Select Committee on Intelligence, who said he learned of the FBI investigation that uncovered the alleged affair on Friday.