Both Allen and Petraeus appear to know Kelley's sister, Natalie Khawam. The men wrote letters in support of the sister in a custody battle, court records show.
Kelley, 37, and her husband have released a statement saying they have been friends with Petraeus and his family for more than five years and asked for privacy.
Petraeus' affair and national security questions
Meanwhile, details continue to emerge Wednesday about the Petraeus affair.
A source familiar with Kelley's version of events said the anonymous e-mails later traced to Broadwell -- which led to the discovery of Petraeus' affair -- began in June. It wasn't until two months later that the FBI told Kelley who had sent the e-mails, said the source, adding that Kelley does not know Broadwell and has never met her.
On Monday, FBI agents were at Broadwell's home in Charlotte, North Carolina, according to spokeswoman Shelley Lynch. She declined to say what the agents were doing there.
A source told CNN national security contributor Fran Townsend that Broadwell was acting as Petraeus' archivist and that the FBI went to the house to look for any documents she might have. It was not clear, the source said, whether any of the material was classified.
The Internet has been abuzz with video of a speech by Broadwell in which she suggested the Libya attack last September 11 was targeting a secret prison at the Benghazi consulate annex, raising unverified concerns about possible security leaks.
"I don't know if a lot of you have heard this, but the CIA annex had actually taken a couple of Libyan militia members prisoner and they think that the attack on the consulate was an effort to get these prisoners back," she said in a speech last month at the University of Denver.
A senior intelligence official denied the claims, saying no prisoners were ever held at the annex. Broadwell did not provide a source for her information, and there's no evidence so far that it came from Petraeus.
Administration officials have said the Benghazi assault was a terrorist attack.
Petraeus was scheduled to testify on Capitol Hill this week about the Benghazi attack at closed-door hearings. Some Republicans have criticized the administration's response to the attack and have speculated that the timing of Petraeus' departure was linked to the congressional inquiry.
Feinstein said Tuesday that she hopes to bring Petraeus before the panel as early as Friday.
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