The Petraeus sex scandal rocked Washington, bringing down one of the most respected military minds of his generation, and with it, exposing a web of intimate and embarrassing electronic communications between the former CIA director and his paramour. It all begged the question:
If the nation's top spy or his mistress - a counterintelligence expert - couldn't keep their private email messages truly private, then who can?
"It's kind of ironic the leader of this organization dedicated to keeping things secret was completely exposed and left hung out to dry," said Cole Stryker, an online privacy and anonymity expert and author of "Hacking the Future."
Stryker said "99.9 percent" of people don't have to worry about the FBI reading their electronic communication. "But obviously there was enough of a reason, with all the implications, for the FBI to chase this one down," he said.
Stewart Baker, a former assistant secretary at the Homeland Security Department who's now in private law practice, agreed.
"As a general matter, the government cant get into your email unless they are conducting an investigation of a crime," he told ABCNews.com.
See the timeline of the Petraeus/Broadwell affair HERE.
The FBI probe began in May or June of this year, sources told ABC News, when Jill Kelley, a Florida socialite and friend of the Petraeus family, began receiving anonymous harassing emails that she believed were referring to the CIA director. She feared his account had been compromised.
Those emails, as the world now knows, turned out to be not-so-anonymous after all.
With the FBI suspicions that Petraeus' email had been compromised, investigators were able to begin a probe into the source of the emails, which ultimately led to the inbox of Paula Broadwell, the retired general's biographer.
"It's harder and harder to maintain anonymity, and particularly if you're engaged in something that could reasonably be viewed as criminal conduct," Baker said.
The FBI uncovered in Broadwell's inbox "hundreds if not thousands of emails between Petraeus and Broadwell," a source told ABC News, many of them salacious in nature and indicating an extramarital affair.
It is unknown whether the FBI utilized its subpoena power on Broadwell's email provider, but Stryker said electronic communication from one account to another leaves footholds for investigators, such as an IP address.
That unique string of numbers can help investigators pinpoint a general location, or, for instance, a specific hotel, where someone may have logged on and sent an email.
Broadwell was first interviewed by FBI agents the week of Oct. 21 and again on Nov. 2, a source told ABC News.
Petraeus, who was made aware of the probe by the FBI during the week of Oct. 29, gave his resignation to President Obama on Nov. 9. It was accepted a day later, ending a storied public career.
For Stryker, the story serves as a lesson for all that very few can achieve anonymity online, whether from a skilled hacker or the FBI.
"Anonymity requires a relentless attention to detail," he said. "You have to be perfect with it or you're sunk."