WASHINGTON: The FBI uncovered the affair that led to the resignation of CIA chief David Petraeus while investigating threatening emails sent by his lover to a second woman, US media reported Sunday.
Petraeus, an American hero credited with turning the tide of the Iraq war, resigned on Friday after admitting an extramarital affair, sending shockwaves around Washington just three days after President Barack Obama's re-election.
It has emerged that his paramour was Paula Broadwell, a 40-year-old former Army major granted unprecedented access to the general as she co-authored a best-selling biography: "All In: The Education of General David Petraeus."
Newspaper reports on Sunday revealed that the affair came to light when the FBI was called in as part of a criminal investigation launched when a second woman complained that she had received vicious emails from Broadwell.
"It didn't start with Petraeus, but in the course of the investigation they stumbled across him," an unnamed congressional official briefed on the matter told The New York Times.
The threatening and harassing emails from Broadwell, a married mother of two, indicated that she thought the other woman was a potential rival for the 60-year-old general's affections, officials told the US media.
A government official told The New York Post that the emails contained such language as: "I know what you did," "back off" and "stay away from my guy."
A senior US military official identified the other woman as 37-year-old Jill Kelley, a State Department liaison officer with Joint Special Operations Command who appears to have had a longstanding friendship with Petraeus.
The recipient of the emails was so frightened, according to the Washington Post, that several months ago she went to the FBI for protection and to help track down the sender.
The FBI soon uncovered Broadwell's sexually explicit correspondence with Petraeus, leading to initial fears of a national security breach if someone had broken into the CIA chief's private Gmail account.
Investigators first interviewed Petraeus "about two weeks ago," law enforcement officials told the Post.
The FBI has concluded that there will not be criminal charges, US media reports said, citing law enforcement sources.