CIA Director David Petraeus resigns, citing extramarital affair WASHINGTON - CIA Director David H. Petraeus abruptly resigned Friday after a brief but troubled tenure as head of America's clandestine spy service, citing his "extremely poor judgment" for engaging in an extramarital affair that the FBI had uncovered in an unrelated investigation. The scandal threw the CIA into turmoil three days after the presidential election and caused consternation at the White House, which had assumed the widely respected former war commander in Iraq and Afghanistan would keep his national security position in the second Obama administration. In a written statement to the CIA workforce, Petraeus said he went to the White House on Thursday afternoon and asked President Obama "to be allowed, for personal reasons, to resign." He said Obama "graciously accepted" his resignation on Friday. "After being married for over 37 years, I showed extremely poor judgment by engaging in an extramarital affair," Petraeus wrote. Citing the "extraordinary work" the CIA had performed, Petraeus added that he "will always regret the circumstances that brought that work with you to an end." The acknowledgment of an affair came as a shock to the national security community. Intelligence officers who engage in illicit behavior may be vulnerable to blackmail by foreign spy services. The CIA has a unusually high turnover rate of directors, but none previously resigned after publicly acknowledging a sexual affair. Two former CIA officials told The Times that FBI inquiries led Petraeus to disclose the affair. Another U.S. official, who was briefed on the case, said Petraeus was not the target of the investigation. NBC News, citing law enforcement officials, reported that Petraeus biographer Paula Broadwell "is under FBI investigation for improperly trying to access his email and possibly gaining access to classified information." Broadwell is the author, with Washington Post journalist Vernon Loeb, of "All In," a favorable Petraeus biography. She had extensive access to Petraeus in Afghanistan. According to her profile on LinkedIn, Broadwell attended the U.S. Military Academy at West Point from 1991 to 1995 and was a major in the Army reserve with "work experience" with the FBI, CIA and the Defense Department. The law enforcement officials told NBC they did not believe the FBI investigation would result in any criminal charges, and that Petraeus was not under investigation. Broadwell did not respond to telephone and email messages. Reached by phone, Loeb said he had no knowledge of whether the reports about Broadwell were true. In a statement, Obama lauded Petraeus for his "extraordinary service" in the military and CIA. He did not mention Petraeus' indiscretion, but said his "thoughts and prayers are with Dave and Holly Petraeus, who has done so much to help military families through her own work. I wish them the very best at this difficult time. Holly Petraeus, a longtime advocate for military families, is assistant director of the Office of Servicemember Affairs at the recently opened Consumer Financial Protection Bureau. Obama named Petraeus' deputy, Michael J. Morell, as interim CIA director. Morell, a career CIA officer, served in that position briefly after Leon E. Panetta left the CIA last year to become Defense secretary. Morell was a witness to two major events in recent history. As a CIA briefer, he was traveling with President George W. Bush on Sept. 11, 2001, when news broke of the terrorist attacks in New York, Pennsylvania and at the Pentagon. And as deputy CIA director, he was in the White House situation room with Obama on May 1, 2011, when U.S. Navy SEALs launched a raid that killed Osama bin Laden in Abbottabad, Pakistan. A White House official said Friday that Morell has a close relationship with Obama, and that he frequently briefed Obama during planning for the raid on Bin Laden's compound. Petraeus, who turned 60 this week, took over as head of the CIA in September 2011. He retired from the military as a four-star general, having played a key role in turning around a deteriorating situation in the Iraq war, and then spending a year commanding the war in Afghanistan, to less certain effect. His military career was seen as giving him a strong advantage as the civilian spy service increasingly ran military-style operations, including lethal drone missile strikes in Pakistan, Yemen and elsewhere. His supporters said he had political ambitions and sometimes offered his name as a possible presidential candidate. But Petraeus' 14-month tenure with the CIA was marked by criticism inside the agency, where he was seen as aloof, and by some lawmakers on Capitol Hill, who said he did not fully respond to their requests. In recent weeks, he faced growing questions about why the CIA failed to anticipate the attack by armed militants on a U.S. diplomatic mission in Benghazi, Libya, despite a large CIA presence in the city. Two of the four Americans killed during the September attack were CIA employees. Petraeus' no-nonsense military style - and some idiosyncrasies - rubbed some CIA managers the wrong way. In May, a leaked CIA cable disclosed that when Petraeus traveled overseas, he wanted fresh pineapple every night before bed, sliced bananas atop his cereal in the morning and predesigned morning runs that avoided intersections. Obsessed with physical fitness, Petraeus pushed a plan to spend up to $25 million expanding two CIA gyms, until colleagues convinced him the austere budget environment made such a proposal unwise. Petraeus also had a rocky relationship with the congressional oversight committees, particularly senior staffers who resented what they viewed as an imperious style and compared him unfavorably with his predecessor, Panetta. But members of those committees rushed to support him Friday. "Petraeus gave the agency leadership, stature, prestige and credibility both at home and abroad," Sen. Dianne Feinstein (D-Calif.), chairwoman of the Senate Intelligence Committee, said in a statement. On a personal level, I found his command of intelligence issues second to none.... I wish President Obama had not accepted this resignation, but I understand and respect the decision. Sen. John McCain (R-Ariz.), ranking member on the Armed Services Committee, said Petraeus "will stand in the ranks of America's greatest military heroes. His inspirational leadership and his genius were directly responsible - after years of failure - for the success of the surge in Iraq.... Our thoughts and prayers are with him and his family. Rep. Peter T. King (R-N.Y.), chairman of the House Committee on Homeland Security, said he regretted Petraeus' resignation. "Gen. Petraeus is one of America's most outstanding and distinguished military leaders and a true American patriot," King said in a statement.