About four years ago , Paula Broadwell began her Ph.D. dissertation on Gen. David Petraeus ' innovative leadership skills . Some of the interviews were done via e-mail . Others were conducted as Broadwell occasionally ran with the physically fit four-star , including one time with Petraeus and his team along the Potomac River in Washington . Broadwell decided to turn that research into a book and go to Afghanistan after Petraeus was tapped in June 2010 to replace Gen. Stanley McChrystal as the top commander in the country . `` We had a relationship before I went there as far as this dissertation was concerned , so it just took it to another level , '' Broadwell told CNN 's Brooke Baldwin in February . Petraeus biographer 's e-mails led FBI to affair , official says . The relationship between Petraeus and his biographer has become the subject of speculation since he admitted to having an extramarital affair and resigned Friday as CIA director . The affair came to light during an FBI investigation into a complaint that Broadwell was sending harassing e-mails to another woman close to Petraeus , a U.S. official said Saturday . During the investigation , other communications surfaced between Petraeus and Broadwell , a married mother of two , according to the official . The official did not identify the woman who made the initial complaint and did not know the nature of her relationship with Petraeus . The FBI interviewed Petraeus in the course of its inquiry , said the official , who stressed that the CIA director was never the target of the investigation and his communications were never compromised . The official did not know whether Broadwell was interviewed . CNN has not been able to reach Broadwell for comment . Her website was not operating Saturday . Broadwell moved with her husband , Scott , to Charlotte , North Carolina , about three years ago , according to the Charlotte Observer . Broadwell , who attended the U.S. Military Academy and served in the Army Reserves after active duty , quickly became a guest on TV news shows after her book , `` All In : The Education of General David Petraeus , '' was published earlier this year . In several appearances on CNN , Broadwell -- with her background in intelligence and counterterrorism -- was asked about U.S. policy in Afghanistan , the Syrian civil war and Iran 's use of nuclear technology . She serves as a research associate at Harvard University 's Center for Public Leadership . Read the Petraeus letter . Broadwell told Baldwin that she embedded with Petraeus ' staff and troops in the field , sharing their hardships and risks . Broadwell spent months in Afghanistan interviewing Petraeus and others for her book , which she wrote with Vernon Loeb . In January , Broadwell told Jon Stewart of `` The Daily Show '' that Petraeus is tenacious , has a will to win and wants to make a difference . `` He loves serving . He loves to be in the arena , '' she said . Just last week , Broadwell published on the Daily Beast a list of Petraeus ' 12 rules for living . `` We all will make mistakes , '' read one rule . `` The key is to recognize and admit them , to learn from them , and to take off the rear-view mirrors -- drive on and avoid making them again . '' How Petraeus changed the U.S. military . Broadwell met Petraeus in spring 2006 when he spoke at Harvard , where she was a graduate student , she wrote in the preface to `` All In . '' The author told the general about her research interests and he agreed to put her in touch with people studying the same issues . `` I later discovered that he was famous for this type of mentoring and networking , especially with aspiring soldier-scholars , '' Broadwell wrote . In the preface , Broadwell -- who earned varsity letters in cross-country and track -- said she wanted to see whether Petraeus could match her stride when they ran . `` Instead , it became a test for me . '' Broadwell 's passion for physical fitness extended to her appearance earlier this year on `` The Daily Show . '' In an effort to raise money for wounded veterans , she and Stewart engaged in a push-up contest . Stewart and Scott Broadwell faced off against Paula Broadwell . A game , but grimacing , Stewart made it to 38 push-ups . Paula Broadwell , apparently ready to do more , stopped at 60 . Ticker : Rep wants Petraeus to testify .
CIA director David Brooks resigned Friday after having an affair . His biographer was investigated over e - mails to another woman , a U.S. official says . Paula Friedman spent months in Afghanistan . She wrote a book about Petraeus ' leadership style .