The sex scandal embroiling America's top spy agency and its former boss is widening.
Ex-CIA director David Petraeus has told friends he was shocked to find that his biographer and girlfriend, Paula Broadwell, was suspected of sending anonymous, threatening emails to a friend of his who she saw as a romantic rival.
A close Petraeus associate says FBI investigators had told Petraeus that Broadwell sent anonymous emails to Jill Kelley, a Petraeus family friend from his time at Central Command in Tampa, warning her to stay away from him.
The CIA director resigned last week after confessing to the affair.
Petraeus was not shown the emails, but was told the tone and content seemed threatening to Kelley, prompting her to report them, the close Petraeus associate said.
That triggered the investigation that led the FBI to Broadwell and evidence of her affair with Petraeus.
The affair began in 2011, two months after he became CIA director, a friend and former top aide said.
The case has sparked an uproar in Congress over FBI investigative tactics and complaints by lawmakers they weren't told soon enough about the probe rocking the intelligence and law enforcement establishment.
The CIA has also been forced to deny an assertion made by Broadwell that it held militants in Libya before the September attack that killed the US ambassador.
During a talk last month at the University of Denver, Paula Broadwell said the CIA had detained people at a secret facility in Benghazi and the attack on the US Consulate was an effort to free those prisoners.
US President Barack Obama issued an executive order in January 2009 stripping the CIA of its authority to take prisoners.
The move means the CIA can no longer operate secret jails as it did under the administration of President George Bush.
CIA spokesman Preston Golson said "any suggestion that the agency is still in the detention business is uninformed and baseless."
Petraeus and his family are said to be devastated over the affair, especially his wife Holly, who "is not exactly pleased right now," said Steve Boylan, a friend and former Petraeus spokesman who spoke to Petraeus over the weekend.
"Furious would be an understatement," Boylan told ABC's Good Morning America. He said Petraeus ended the affair four months ago.
Members of Congress said they want to know more details about the FBI investigation that revealed the extramarital affair between Petraeus and Broadwell.
They questioned when the retired general popped up in the FBI inquiry, whether national security was compromised and why they weren't told sooner.
Petraeus, 60, has been married 38 years to Holly Petraeus, with whom he has two adult children, including a son who led an infantry platoon in Afghanistan as an Army lieutenant.
Broadwell, a 40-year-old graduate of the US Military Academy and an Army Reserve officer, is married with two young sons.
THE OTHER WOMAN
According to a senior US military official, Kelley, 37, lives in Tampa and serves as an unpaid social liaison to MacDill Air Force Base, 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 US 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 US government.
In a statement Sunday, Kelley and her husband, Scott, said: "We and our family have been friends with General 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."
The military official who identified Kelley spoke on condition of anonymity because he was not authorised to publicly discuss the investigation.
He said Kelley had received harassing emails from Broadwell, which led the FBI to examine her email account and eventually discover her relationship with Petraeus. It was not clear what led Broadwell to send the emails to Kelley.
The FBI contacted Petraeus and other intelligence officials, and Director of National Intelligence James Clapper asked Petraeus to resign.
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.
Boylan said Petraeus was keenly aware that he has injured his family while losing "one of the best jobs he ever had. He's devastated."
Petraeus' affair with Broadwell will be the subject of meetings this week involving congressional intelligence committee leaders, FBI deputy director Sean Joyce and CIA deputy director Michael Morell.
Petraeus had been scheduled to appear before congressional committees on Thursday to testify about the September 11 attack on the US Consulate in Benghazi, Libya, that killed four Americans, including US Ambassador Chris Stevens.
Morell was expected to testify in place of Petraeus, and lawmakers said he should have the answers to their questions.
Clapper was told by the Justice Department of the Petraeus investigation last week at about 5pm on America's election day, and then called Petraeus and urged him to resign, according to a senior US intelligence official who spoke on condition of anonymity because he was not authorised to discuss the investigation publicly.
FBI officials said the congressional committees weren't informed until Friday, one official said, because the matter started as a criminal investigation into harassing emails allegedly sent by Broadwell to Kelley.
Concerned that emails Petraeus exchanged with Broadwell raised the possibility of a security breach, the FBI brought the matter up with him directly, according to the official.
Petraeus decided to quit, though he was breaking no laws by having an affair, officials said.