PHOTOS: Jill Kelley, woman reportedly harassed by Paula Broadwell in possible Petraeus blackmail scandal

More details regarding the FBI investigation that led to the resignation of David Petraeus have been revealed over the last several hours.

37-year old Jill Kelley, a friend of the Petraeus family, reportedly alerted the FBI about threatening emails that appeared to blackmail the CIA director.

Kelley of Tampa, Florida is married with three children. She and her sister are close friends of the Petraeus family and sometimes vacation together. Sources indicate that she was not involved in an affair with the former CIA chief.

The FBI was investigating harassing emails sent by Petraeus biographer and girlfriend Paula Broadwell to a second woman. That probe of Broadwell's emails revealed the affair between Broadwell and Petraeus. The FBI contacted Petraeus and other intelligence officials, and Director of National Intelligence James Clapper asked Petraeus to resign.

A senior U.S. military official identified the second woman as Jill Kelley, 37, who lives in Tampa, Fla., and serves as an unpaid social liaison to MacDill Air Force Base in Tampa, where the military's Central Command and Special Operations Command are located.

Staffers for Petraeus said Kelley and her husband were regular guests at events he held at Central Command headquarters. A U.S. official said the coalition countries represented at Central Command gave Kelley an appreciation certificate on which she was referred to as an "honorary ambassador" to the coalition, but she has no official status and is not employed by the U.S. government.

The official, speaking on condition of anonymity because he wasn't authorized to discuss the case publicly, said Kelley is known to drop the "honorary" part and refer to herself as an ambassador.

The military official, who spoke on condition of anonymity because he was not authorized to publicly discuss the investigation, said Kelley had received harassing emails from Broadwell, which led the FBI to examine her email account and eventually discover her relationship with Petraeus.

A former associate of Petraeus confirmed the target of the emails was Kelley, but said there was no affair between the two, speaking on condition of anonymity to discuss the retired general's private life. The associate, who has been in touch with Petraeus since his resignation, says Kelley and her husband were longtime friends of Petraeus and wife, Holly.

The Telegraph confirms the friendship between the Kelley and Petraeus families.

Paula Broadwell, the former CIA director’s biographer and reported lover, allegedly sent a number of threatening messages to Jill Kelley, a 37-year-old civilian who organised parties for the US military, who became frightened and turned to the FBI for help.

...Although the emails, believed to have been sent anonymously by Mrs Broadwell, 40, were said to have contained hints at classified information, the FBI concluded that there was no security threat and that they were instead looking at a case of lover’s jealousy.

According to The New York Post, Mrs Broadwell, a mother of two, told Mrs Kelley: “I know what you did” and warned her to “back off” from the 60-year-old former general.

"We and our family have been friends with Gen Petraeus and his family for over five years. We respect his and his family's privacy and want the same for us and our three children," Mrs Kelley said in a statement.

Photographs showed the Petraeuses and the Kelleys posing together at a pirate-themed festival in 2010 and ABC News reported that the families had spent Christmases together.

It is not clear why Mrs Broadwell would believe that the mother-of-three, posed a threat to her relationship with the general.

Members of Congress on both sides of the aisle want to know whether national security was compromised for political reasons.

Members of Congress said Sunday they want to know more details about the FBI investigation that revealed an extramarital affair between ex-CIA Director David Petraeus and his biographer, questioning when the retired general popped up in the FBI inquiry, whether national security was compromised and why they weren't told sooner.

"We received no advanced notice. It was like a lightning bolt," said Democratic Sen. Dianne Feinstein of California, who heads the Senate Intelligence Committee.

The critical question: how long did the Justice Department freeze the story, thereby endangering U.S. national security?