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FBI investigators confronted then CIA Director David Petraeus within the last six weeks about his relationship with biographer Paula Broadwell, Fox News has learned -- a detail that comes as lawmakers complain they did not know about the issue until Petraeus resigned Friday.

A source, who is not authorized to speak on the record about the FBI investigation due to its sensitive nature, characterized the meeting between Petraeus and Bureau agents as “recent, and within the last six weeks.”

Asked when Broadwell was confronted, Fox News was told “a little before that.”

Asked why the FBI did not brief Congress immediately when Petraeus’ name surfaced within the scope of the investigation, the source said decisions on notification “should all play out next week” -- a reference to a half dozen Capitol Hill hearings and briefings on the Benghazi consulate attack.

The source said the Bureau’s apparent decision not to notify relevant lawmakers, in this case the chair and ranking members of the House and Senate Intelligence Committees, was characterized as a “balance (between) the facts, the circumstances that apply, whether it is an ongoing criminal matter, whether concerns over intelligence have been resolved.”

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Even if the investigation and its findings did not fall within the literal terms of the statutes that govern Congressional notification, a former senior Justice Department official under the Bush administration said the FBI should have erred on the side of caution.

“I think the FBI would have been well advised to notify Congress as soon as it had reasonable ground to suspect Petraeus of misconduct and had begun an investigation," Tom Dupree told Fox News.

Given the investigation began in the early summer, around June, Dupree said the purpose of the FBI’s disclosure requirement is to ensure that Congress has the information necessary to perform its oversight function.

“Given the obvious significance of this information as to whether Petraeus could continue to serve as CIA Director, it is something Congress would plainly have wanted to know given its impact on US intelligence operations.

And the reasons that sometimes counsel against disclosure -- e.g. Compromising operational security -- certainly don’t apply here."

Sen. Dianne Feinstein, chairwoman of the Senate Select Committee on Intelligence, said Sunday the Capitol Hill investigations into the Libya terrorist attack also will address the scandal surrounding Petraeus, including why the FBI failed to notify the committee about the extramarital affair that led to the director’s resignation.

The California Democrat told “Fox News Sunday” she found out about Petraeus’ resignation Friday as the rest of world learned the news and described being shocked and “heartbroken.”

“We will investigate why the committee didn’t know,” Feinstein said. “We should have been told.”

She also said the first committee meeting, scheduled for Thursday, is the start of an inquiry, not a hearing. Feinstein said Petraeus is no longer scheduled to testify but could be summonsed to Capitol Hill for future meetings. A similar, closed-door House intelligence committee hearing also is scheduled for Thursday.

Feinstein said she sees “absolutely” no connection between the director’s resignations and the unanswered questions about the Sept. 11 attacks in Benghazi, Libya, in which Ambassador Christopher Stevens and three other Americans were killed.

What is publicly known about the timeline suggests Broadwell learned she was the subject of an FBI investigation as early as September and Petraeus shortly thereafter.

The knowledge that Petraeus was under scrutiny by the FBI, and he knew he was under scrutiny, may have cast his statements in a different light.

Before the CIA director’s resignation, senior lawmakers complained to Fox News about a briefing Petraeus gave on Sept.14 about the Benghazi consulate attack.

Two days after the deadly Libya terror attack, on Sept. 13, representatives of the FBI and National Counterterrorism Center gave Capitol Hill briefings in which they said the evidence supported an Al Qaeda or Al Qaeda-affiliated attack.  Fox News was told there was no mention of a demonstration or any significant emphasis on the anti-Islam video that for days was cited by administration officials as a motivating factor.

Fox News was told that the Petraeus briefing on Sept. 14 conflicted with that of the FBI and NCTC.  On Capitol Hill, Petraeus characterized the attack as more consistent with a flash mob, where the militants showed up spontaneously with RPGs. Petraeus downplayed to lawmakers the skill needed to fire mortars, which also were used in the attack and to some were seen as evidence of significant pre-planning.

Lawmakers at the briefing said that Petraeus seemed wedded to the narrative that the attack was linked to a demonstration and was spontaneous as opposed to pre-meditated.