Unlike many stories about powerful Washington figures having secret affairs, the downfall of spy chief David Petraeus goes beyond sex.

The scandal surrounding the decorated four-star Army general who once ran the wars in Iraq and Afghanistan involves questions of national security, politics and even the September 11 attack on the U.S. consulate in Benghazi, Libya, that left four Americans dead.

Petraeus, 60, resigned Friday after acknowledging he had an affair with a woman later identified as his biographer, Paula Broadwell, 40, a fellow West Point graduate who spent months studying the general's leadership of U.S. forces in Afghanistan.

FBI agents were at Broadwell's Charlotte, North Carolina, home late Monday, said local FBI spokeswoman Shelley Lynch. She declined to say what the agents were doing there.

Video from CNN affiliate WCNC showed a handful of people getting out of vehicles, carrying boxes and bags into the house. None spoke to reporters, even when asked who they were.

Days after Petraeus' resignation stunned Washington, information continues to emerge. Among other things, a video has surfaced of a speech by Petraeus' paramour in which she suggested the Libya attack was targeting a secret prison at the Benghazi consulate annex, raising unverified concerns about possible security leaks.

The affair came to light during an FBI investigation of "jealous" e-mails reportedly sent by Broadwell to a woman named Jill Kelley, a government source familiar with the investigation told CNN on Monday.

Kelley, 37, and her husband Scott released a statement saying they have been friends with Petraeus and his family for more than five years and asked for privacy.

Although Kelley lives in Tampa, Florida, she's known as a member of Washington's social circuit, according to the government source. The source has not spoken to Kelley, but says friends describe her as feeling like she is an "innocent victim."

Petraeus has denied having an affair with anyone other than Broadwell, according to a friend of the former general who has spoken with him since news of the affair broke.

The scandal also is rumbling through the halls of Congress, where leaders in both parties are seeking answers about the FBI investigation and there's much speculation about the impact Petraeus' resignation will have into the inquiry into the Benghazi attack.

Petraeus was scheduled to testify on the attack and the government's reaction to it this week.

Here's a look at the major threads of this still-unfolding story:

Why does it matter? Security and Benghazi

While affairs may be commonplace in Washington, when they involve the director of the CIA, things can take on a different tone.

Analysts say there is no evidence that a security breach occurred as a result of the affair, but that hasn't stopped discussion that Broadwell could have gained access to classified information as a result of what she has routinely described as "unprecedented access" to Petraeus.

That discussion seemed to gain momentum Monday thanks to comments Broadwell made in a speech last month at the University of Denver.

"I don't know if a lot of you have heard this, but the CIA annex had actually taken a couple of Libyan militia members prisoner and they think that the attack on the consulate was an effort to get these prisoners back," Broadwell said.

A senior intelligence official told CNN on Monday, "These detention claims are categorically not true. Nobody was ever held at the annex before, during, or after the attacks."

Broadwell's source for that previously unpublished bit of information remains unclear, and there's no evidence so far that it came from Petraeus. Administration officials have said the Benghazi assault was a terrorist attack.

The New York Times also reported Sunday that investigators found classified documents on Broadwell's laptop computer. The newspaper cited investigators as saying Petraeus denied he had given them to her.

Retired Gen. James "Spider" Marks, for whom Broadwell once worked and who knows Petraeus, said he doubts security protocols were breached despite what seems an unlikely indiscretion on the part of Petraeus.

"There's almost zero percent chance that national security was compromised or at risk," he said Monday.

A senior U.S. intelligence official said an extramarital affair by a CIA officer is not automatically considered a security violation.

"It depends on the circumstances," the official said.

The official also said Broadwell did not have a security clearance from the CIA.

Another official said Broadwell, who is an officer in the Army reserve, did have some kind of security clearance and that there are no issues with Broadwell having unauthorized access to classified information.

Petraeus' resignation also presents challenges to the congressional inquiry into the Benghazi attack.

CNN has confirmed that Petraeus recently traveled to Libya to meet the CIA station chief to discuss the attack. He was scheduled to testify before a congressional committee this week on the assault and the U.S. government response to it.

That now will not happen, but it is possible that he could be summoned by Congress to testify later.

Some Republicans have criticized the administration's response to the Benghazi attack and have speculated that Petraeus' departure was linked to the congressional inquiry.

Rep. Peter King, R-New York, said elements of the story "don't add up." He called Petraeus "an absolutely essential witness, maybe more than anybody else."

However, a senior U.S. official said Petraeus' departure wasn't connected to the Benghazi hearing.

"Director Petraeus' frank and forthright letter of resignation stands on its own," said the official, who spoke on the condition of anonymity because of the sensitivity of the topic. "Any suggestion that his departure has anything to do with criticism about Benghazi is completely baseless."

The investigation

Congressional leaders are calling for an explanation of why they weren't notified sooner of the FBI's inquiry when it became clear Petraeus was involved.

Leaders of the House Intelligence Committee are expected to meet Wednesday with acting CIA Director Mike Morell and FBI Deputy Director Sean Joyce to discuss the Petraeus investigation and congressional oversight.

Sen. Diane Feinstein, the Democratic chair of the Senate Intelligence Committee, said on "Fox News Sunday" that she would "absolutely" push for answers.

"I mean, this is something that could have had an effect on national security," she said. "I think we should have been told. There is a way to do it. And that is, just to inform the chair and the vice chairman of both committees, to -- this has happened before, not with precise, same things, but, none of the four of us have ever breached that confidentiality."

On Monday, Feinstein told NBC that her concern about the situation "has actually escalated the last few days."