FBI investigation of threatening emails revealed Petraeus affair WASHINGTON - The extramarital affair that ended the public career of CIA Director David H. Petraeus was uncovered when a woman described as close to him received harassing emails and complained to authorities, a U.S. official confirmed Saturday. The FBI traced the emails and found that they had been sent by Paula Broadwell, who wrote a highly favorable book on the former Army general's life and work. While investigating Broadwell, the FBI found additional emails that discussed her relationship with Petraeus, revealing their affair. The New York Times and Washington Post reported these details Saturday afternoon. The emails sent by Broadwell indicated that she perceived the other woman as a threat to her relationship with Petraeus, law enforcement officials told the Washington Post. Director of National Intelligence James R. Clapper learned about the affair from the FBI about 5 p.m. Tuesday, election day, an intelligence official said. As a colleague, former general and friend, Clapper advised Petraeus to resign as CIA director. Clapper informed the White House on Wednesday. Petraeus, 60, met Thursday with President Obama, who accepted his resignation Friday. The U.S. official who confirmed the information - who, like the intelligence official, asked to remain anonymous in discussing internal matters - said the White House was not aware of the FBI email investigation until Wednesday, noting that it is not briefed on "every routine investigation." The U.S. official explained that this was an "unrelated investigation" that had pulled in Petraeus. Broadwell, a married mother of two young sons, apparently had no idea any of this was coming. Last week, her husband was making preparations for her 40th birthday party to be held Saturday night in Washington. The guest list included government officials and journalists. On Friday, hours after media outlets linked Broadwell to the affair, came an email from Scott Broadwell, a radiologist: "The party is canceled on Saturday. Paula Broadwell has not responded to emails or phone messages. By her own accounts, Broadwell had an unusually close-up view of Petraeus' duties while he commanded the war effort in Afghanistan and she researched her book. "I was entrusted with this opportunity to sit in on high-level meetings with Gen. Petraeus ... listen to classified chatter of terrorists talk and so forth," Broadwell said at a national security conference in July. I knew there was a clear line that I couldn't cross.... It was my responsibility not to leak it, not to violate my mentor, if you will - I was writing about a very close mentor. Broadwell, a self-described soccer mom who lives with her family in a $900,000 house in Charlotte, N.C., is a high-octane achiever, a triathlete with degrees from West Point and Harvard. She holds the rank of major in the Army Reserve, and she said she held a top-secret "sensitive compartmented information" clearance, one of the highest. She is a research associate at Harvard's Center for Public Leadership and a doctoral candidate in the Department of War Studies at King's College London, according to her biography on Penguin's website. Broadwell first met Petraeus in 2006 when he spoke at Harvard's Kennedy School of Government, where she was a graduate student. When she told him about her research interests in counter-terrorism and counterinsurgency, he handed her his card and offered his help. With his support, she told the Charlotte Observer, she used Petraeus as a subject in a dissertation on leadership. Soon enough she had an agent for a book. She teamed up to write it with Vernon Loeb, the local editor at the Washington Post who reported on Petraeus when the general led the 101st Airborne Division in the Iraq war. The book, "All In: The Education of General David Petraeus," was published in January and won some favorable reviews, with many critics mentioning Broadwell's unparalleled close perspective on the general's activities. One reviewer, Andrew Marble, noted in the Washington Independent Review of Books that there seemed to be a lack of distance between author and subject: "In many places it is unclear whether a particular statement or perspective belongs to Broadwell, Petraeus himself or others." Even after Petraeus had become CIA director in September 2011 and the book was published, it was clear Broadwell continued to have close journalistic access to Petraeus and remained familiar with his schedule. At the Aspen Security Forum in July, Broadwell told several attendees that Petraeus had accepted an invitation to the event, but the White House had told him not to go to avoid making news. In January, The Times published an article quoting congressional sources suggesting that members of the intelligence oversight committees were unhappy with Petraeus' responsiveness to them. Broadwell emailed The Times with the subject line: "article on P4," using the military nickname for Petraeus, who retired as a four-star general. "For the record, he does spend a lot of time on the Hill," she wrote. Back today for closed door sessions. I think he is there weekly. Broadwell appeared on "The Daily Show with Jon Stewart" to promote her book. She recounted how she interviewed Petraeus on six-mile runs and mentioned Petraeus' high-school nickname was "Peaches." "He loves serving," Broadwell said of Petraeus. He loves to be in the arena. Stewart joked that the main controversy the book stirred was whether Petraeus was "awesome, or incredibly awesome." In an online-only portion of the show, Broadwell challenged Stewart to a push-up contest to raise money for a charity for wounded veterans. Scott Broadwell walked up on stage to join Stewart, who pledged $1,000 for each push-up Paula Broadwell could do beyond the men's count. The tally was 59 for Paula Broadwell; 38 for the two men, combined. Christi Parsons in the Washington bureau contributed to this report.