WASHINGTON // It started in May with a spiteful email to the top US commander in Afghanistan. An anonymous writer warned Gen John Allen that a friend he was meeting in Washington the next week was trouble and he should stay away from her.
Gen Allen thought the email was a joke as he could not understand how anyone else would know about his personal plans with his friend, Florida socialite Jill Kelley, a person close to Ms Kelley said.
That email began a chain of events that led to the downfall of the CIA director, David Petraeus, put Gen Allen's career on hold and landed a decorated FBI agent in hot water for talking about an ongoing investigation.
The FBI traced that email and others of a similar vein to Paula Broadwell, Mr Petraeus' biographer, who agents would soon learn had also been his lover.
The fast-moving scandal broke just days after US president Barack Obama was elected to a second term in office. Mr Obama's administration had been on the defensive for weeks because of a terror attack on the US consulate in Benghazi, Libya, that left four Americans dead.
Briefings on the attack had been postponed until after the election and are now focused more on Mr Petraeus' love life than on how terrorists were able to attack the poorly defended consulate. Mr Obama said on Wednesday that he's seen no evidence that national security was damaged by the revelations that ended his CIA director's career and imperil that of his Afghanistan war chief.
But legislators are not taking Mr Obama's word for it and have grilled FBI and CIA officials privately about the same issues: whether national security was jeopardised by the case and why they did not know about the investigation sooner.
The FBI's investigation of the matter began last summer when Ms Kelley turned over anonymous emails that had been sent to her and Gen Allen. The first was sent to Gen Allen in May, under the pseudonym "Kelleypatrol," the person close to Ms Kelley said.
In middle of the summer, Ms Kelley shared these emails with an FBI agent, Frederick W Humphries, who she met at an FBI community programme last year. Concerned that someone was tracking the movements of Gen Allen and Mr Petraeus, Humphries set the investigation in motion when he handed the information to the FBI's cyber squad in Tampa.
But Mr Humphries was cut out of the loop and took that to mean the FBI was not taking the case seriously, the source said.
Mr Humphries would later reach out to Congress in a whistle-blower role that has now landed him under internal scrutiny at the bureau.
But the FBI was taking the case seriously and continues to investigate. The bureau has found a substantial number of classified documents on Ms Broadwell's computer and in her home, according to a law enforcement official.
Ms Broadwell has told agents that she took classified documents out of security government buildings, the official said.
Unauthorised possession of classified national defence documents is a crime. The Army has suspended Ms Broadwell's security clearance, which she had as a former Army intelligence officer.
The FBI also found emails between Ms Kelley and Gen Allen that were turned over to the Defense Department for investigation. Mr Obama has put on hold Gen Allen's nomination to become the next commander of US European Command as well as the Nato supreme allied commander in Europe until Pentagon investigators are able to sift through the emails that involve Gen Allen and Ms Kelley.
Gen Martin Dempsey, chairman of the Joint Chiefs of Staff, said yesterday he still expects Gen Allen to eventually take over the European Command but acknowledged, "I see this investigation and how long it could take affecting that."
Gen Dempsey said "I absolutely have confidence" in Gen Allen's ability to continue in command in Afghanistan despite the distraction of the scandal.
The FBI director, Robert Mueller, and the deputy director, Sean Joyce, met legislators privately on Wednesday to explain how the investigation unfolded.
Acting CIA Director Michael Morell went before the house panel next, after meeting a day earlier with top senate intelligence officials to explain the CIA's take on events that led to Mr Petraeus' resignation.
The questioning on Capitol Hill was continuing yesterday.
And Ms Kelley's decision to contact her friend at the FBI continues to reverberate months later. Her own pass to enter MacDill Air Force Base in Florida had been indefinitely suspended, a move that ends her easy access to the senior military officials in her social world.