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Petraeus revelation began as cyber-harassment probe; investigation ended 4 days before election

Officials say the FBI investigation into David Petraeus was triggered  by a complaint from a family friend into emails sent by his biographer Paula Broadwell. NBC's Andrea Mitchell reports.

After investigating a potential case of "cyber-harassment" for several months, the FBI wrapped up its case after interviewing Paula Broadwell -- the biographer of former CIA director David Petraeus -- on Friday, Nov. 2, four days before the presidential election, a senior U.S. law enforcement official told NBC News.

It was the second time that FBI agents had questioned Broadwell in the probe and during both interviews she acknowledged having had an affair with Petraeus, the official said. Petraeus himself had been questioned a few days earlier and also acknowledged the affair, the first official said.

The dual interviews the week of Oct. 29 -- among the last to be conducted by the FBI in the case -- allowed the FBI to formally conclude there was no basis for criminal charges in the matter. This explains why the Director of National Intelligence James Clapper wasn't told about the probe until the following Tuesday, Nov. 6, election day, the official said.

The official offered new details about the FBI investigation -- and a more precise timeline of key events-- in order to rebut suggestions that senior law enforcement officials held back key information about the Petraeus matter until after the election.

The FBI and Justice Department's decisions on the case were not governed by the political calendar, the official asserted. Nor, the official said, were they influenced by a phone call from House Majority Leader Eric Cantor's office to the FBI on Oct. 31 asserting that it had heard from a FBI whistleblower who raised concerns that the Petraeus matter was being covered up or not being taken seriously.

Lawmakers question timing of Petraeus resignation

"I was contacted by an FBI 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,” Cantor said in a statement.

According to reporting by NBC’s chief justice correspondent Pete Williams, a senior law enforcement official said a call to a congressional staffer came from an agent who was initially involved in the investigation but who was later removed from the case because he knew an associate of one of the people being investigated.  The agent knew someone on the Hill and called that person, a Republican staffer, according to the official. But that phone call had no effect on either the course of the investigation, the involvement of Mueller -- who was following it closely long before Cantor called him -- or the decision to notify Clapper, the official says.

"This had nothing to do with the election," the official said. Moreover the official added, Cantor's office was told that the case was being actively investigated by the FBI when it raised the matter on Oct. 31, and so it would have been wrong for the FBI or Justice Department to inform higher level officials in the administration about the probe earlier -- because they were unsure at that point what they were dealing with. In the end, according to multiple officials, investigators determined there was no criminal wrongdoing.

The woman who complained of being harassed by Paula Broadwell, General David Petraeus' biographer, has been identified as Jill Kelley, 37, a senior official tells NBC News. NBC's Kristen Welker reports.

According to the senior official, the investigation began several months ago when a woman reported to the FBI she had received anonymous-- and harassing -- emails from a person she didn't know. Multiple government officials tell NBC News that the woman was Jill Kelley, who lives in Tampa, Florida. Kelley and her husband, officials say, are close friends of the Petraeus family. Kelley was a volunteer social liaison to the MacDill Air Force Base in Tampa.

The FBI viewed the matter as a potential case of "cyber-harassment" and it was handled "regionally" with federal prosecutors working with the FBI on the matter, the official said. At first, neither Kelley nor the FBI knew who was sending the harassing emails-- because they came from accounts that were not immediately identifiable. But the FBI was eventually able to determine they came from Broadwell and then obtained access to her regular email account. It was only then that the FBI discovered, through her email exchanges with Petraeus, an apparent relationship between the two of them, the official said.

The FBI continued investigating the matter and was close to wrapping up the case late in October, the official said. Agents finally interviewed Petraeus the week of Oct. 29 and then re-interviewed Broadwell, allowing them to complete their investigation, according to multiple officials. It was only at that point that the decision was made to pass along information about the case to Clapper, the senior law enforcement official said, setting in motion the chain of events that led to Petraeus' resignation.

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NBC's Kristen Welker contributed to this report.