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FBI visits Petraeus' home, sources tell NBC News

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Meet the people who have been pulled into the scandal that caused Gen. David Petraeus to resign.

FBI agents visited the home of former CIA director David Petraeus on Friday, two sources with knowledge of their visit told NBC News.

USA Today reported Friday that the agents went there to "interview" Petraeus, but it's unclear whether he was at his home in suburban Washington. Officials said the visit didn't indicate any new development in the FBI's months-long investigation into allegations that writer Paula Broadwell improperly received or stored classified documents while she was working on Petraeus' biography.

Petraeus, who was commander of U.S. and U.N. forces in Afghanistan in 2010 and 2011, resigned as head of the CIA in November after it was revealed that he had an affair with Broadwell. Petraeus apologized for the affair in a rare public appearance last month.

Officials said one reason the investigation has dragged on for so long is that each document at issue must be thoroughly checked to determine whether it was properly classified and, if so, whether it was still classified at the time it was allegedly in Broadwell's possession.

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