TAMPA, Florida (AP) _ The FBI is preparing a timeline of its criminal investigation that brought to light CIA Director David Petraeus’ extramarital affair so the bureau can respond to members of Congress asking why they and the White House weren’t notified of the probe months ago.

Meanwhile, FBI agents on Monday searched the home of the woman with whom Petraeus had the affair. And the Pentagon began investigating alleged “inappropriate communications” between the top U.S. commander in Afghanistan and a second woman involved in the case.

The White House wasn’t informed of the FBI investigation that involved Petraeus until Nov. 6, Election Day, although agents began looking at Petraeus’ actions months earlier, sometime during the summer. Senate Intelligence Committee chairwoman Dianne Feinstein complained that she first learned of the matter from the media late last week, and confirmed it in a phone call to the then-CIA director on Friday.

That was the same day President Barack Obama accepted Petraeus’ resignation, and the 60-year-old retired Army general, who headed U.S. military operations in Iraq and Afghanistan before taking charge of the CIA, acknowledged an affair with his 40-year-old biographer, Paula Broadwell, and expressed regret.

Defending the notification timing, a senior federal law enforcement official pointed Monday to longstanding policies and practices, adopted following abuses and mistakes that were uncovered during the Nixon administration’s Watergate scandal of the early 1970s. The Justice Department _ of which the FBI is part _ is supposed to refrain from sharing detailed information about its criminal investigations with the White House.

To the extent there is any Justice-White House contact on sensitive criminal investigations, the interaction is supposed to take place between the White House counsel’s office and the office of the Deputy Attorney General, Justice’s second-ranking official. Direct White House contact with the department’s criminal division and its investigators on sensitive probes is out of bounds.

But lawmakers are also asking whether White House national security executives and senior members of Congress should have been notified earlier because the FBI, in addition to its criminal investigation of an alleged email harassment case, also looked into whether a separate set of emails between Petraeus and Broadwell might involve any security breach. That will be a key question Wednesday in meetings involving congressional intelligence committee leaders, FBI deputy director Sean Joyce and CIA deputy director Michael Morell.

The federal law enforcement official said the FBI had concluded relatively quickly _ and certainly by late summer at the latest _ that there was no security breach. Absent a security breach, it was appropriate not to notify Congress or the White House earlier, this official said.

Feinstein said she didn’t understand why the FBI didn’t give her a heads-up as soon as Petraeus’ name emerged in the investigation. “We are very much able to keep things in a classified setting,” she said.

Extramarital affairs are viewed as particularly risky for intelligence officers because they might be blackmailed to keep the affair quiet. For military personnel, adultery is a crime under the Uniform Code of Military Justice.

As this debate began to crank up in the nation’s capital, part of the FBI investigation was still under way in North Carolina, where FBI agents conducted a search of Broadwell’s Charlotte home Monday night.

Also, the Pentagon said Monday that the top American commander in Afghanistan, Gen. John Allen, is under investigation for alleged “inappropriate communications” with a woman who is said to have received threatening emails from Broadwell.

According to two federal law enforcement officials, the FBI initially began a criminal investigation of unsigned, harassing emails that were sent, beginning last May, to Tampa socialite Jill Kelley. She and her husband, Scott, were longtime friends of Petraeus and his wife, Holly. FBI agents traced the alleged cyber harassment to Broadwell and during that process discovered she was exchanging intimate messages with a private Gmail account. Further investigation revealed that account belonged to Petraeus, under an alias.

Petraeus and Broadwell apparently used a trick, known to terrorists and teenagers alike, to conceal their email traffic, one of the law enforcement officials said.

Rather than transmitting emails to the other’s inbox, they composed at least some messages and instead of transmitting them, left them in a draft folder or in an electronic “dropbox,” the official said. Then the other person could log onto the same account and read the draft emails there. This avoids creating an email trail that is easier for outsiders to intercept or trace.

Agents later told Petraeus that Broadwell sent emails warning Kelley to stay away from the general and carrying a threatening tone.

Friends and former staff members of Petraeus told The Associated Press that he has assured them his relationship with Kelley was platonic, although Broadwell apparently saw her as a romantic rival. They said Petraeus was shocked to learn last summer of Broadwell’s emails to Kelley.

Petraeus also denied to these associates that he had given Broadwell any sensitive military information.

FBI agents who contacted Petraeus told him that sensitive, possibly classified documents related to Afghanistan were found on her computer, the general’s associates said. He assured investigators they did not come from him, and he mused to his associates that they were probably given to her on her reporting trips to Afghanistan by commanders she visited in the field there.

One associate also said Petraeus believes the documents described past operations and had already been declassified, although they might have still been marked “secret.”

Broadwell had high security clearances as part of her former job as a reserve Army major in military intelligence. But those clearances are only in effect when a soldier is on active duty, which she was not at the time she researched the Petraeus biography.

The FBI concluded there was no security breach.

But the criminal investigation continued into the emails to Kelley, including whether Petraeus had any hand in them. At that point in late summer, FBI Director Robert Mueller and eventually Attorney General Eric Holder were notified that agents had uncovered what appeared to be an extramarital affair involving Petraeus.

Broadwell and Petraeus have each been questioned by FBI agents twice in recent weeks, with both acknowledging the affair in separate interviews. The FBI’s most recent interviews with Broadwell and with Petraeus both occurred during the week of Oct. 29, days before the election, one of the law enforcement officials said. The FBI notified Obama’s director of national intelligence, James Clapper, of the investigation on Tuesday, Nov. 6 _ Election Day.

There were at least a couple of members of Congress who heard inklings of the affair before the election. Republican Rep. Dave Reichert of Washington state received a tip from an FBI source that the CIA director was involved in an affair in late October. Reichert arranged for an associate of his source at the FBI to call House Majority Leader Eric Cantor on Saturday, Oct. 27, according to Cantor spokesman Rory Cooper.

Cooper told The Associated Press Monday that Cantor notified the FBI’s chief of staff of the conversation but did not tell anyone else because he did not know whether the information from a person he didn’t know was credible.

“Two weeks ago, you don’t want to start spreading something you can’t confirm,” Cooper said.

The FBI responded by telling Cantor’s office that it could not confirm or deny an investigation, but assured the leader’s office it was acting to protect national security. Cooper said Cantor believed that if national security was affected, the FBI would, as obligated, inform the congressional intelligence committees and others, including House Speaker John Boehner.

The FBI agent who contacted Reichert was the same one who first received the allegations from Kelley, a federal law enforcement official said Monday night. That agent’s role in the case consisted simply of passing along information from Kelley to the FBI agents who conducted the investigation, but that agent was subsequently told by his superiors to steer clear of the case because they grew concerned that the agent had become obsessed with the investigation, the official said. The agent was a friend of Kelley and long before the case involving Petraeus got under way, the agent had sent Kelley shirtless photos of himself, according to this official.

Broadwell co-authored a biography titled “All In: The Education of General David Petraeus,” published in January. She wrote that she met Petraeus in the spring of 2006 while she was a graduate student at the Kennedy School of Government at Harvard and she ended up following him on multiple trips to Afghanistan as part of her research.

Petraeus, 60, told one former associate he began an affair with Broadwell, 40, a couple of months after he became CIA director in September 2011. They mutually agreed to end the affair four months ago, but they kept in contact because she was still writing a dissertation on his time commanding U.S. troops overseas, the associate said.

Petraeus told former staffers and friends that he had regularly visited the Kelleys’ home overlooking Tampa Bay. Jill Kelley, 37, served as a sort of social ambassador for U.S. Central Command, hosting parties for the general when Petraeus was commander there from 2008-10.

Jill Kelley regularly kept in touch with Petraeus when he became commander of the Afghanistan war effort, the two exchanging near-daily emails and instant messages, two of his former staffers said. But those messages were exchanged in accounts that his aides monitored as part of their duties and were not romantic in tone, the staffers said.

Petraeus and his family are devastated over the affair _ especially Mrs. Petraeus, who “is not exactly pleased right now” after 38 years of marriage, said Steve Boylan, a friend and former Petraeus spokesman who spoke to him over the weekend.

Broadwell, married with two young sons, has not returned phone calls or emails seeking comment.

Petraeus had been scheduled to appear before congressional committees Thursday to testify about the Benghazi, Libya, attack that killed four Americans, including U.S. Ambassador Chris Stevens. Petraeus’ deputy and acting successor, Morell, is now expected to testify instead.

Feinstein and others didn’t rule out the possibility Congress will try to compel Petraeus to testify about Benghazi later.