Once Broadwell was identified, FBI agents would have gone to Internet service providers with warrants for access to her accounts. Experts said companies typically comply by sending discs that contain a sender’s entire collection of accounts, enabling the FBI to search the inbox, draft messages and even deleted correspondence not yet fully erased.
“You’re asking them for e-mails relevant to the investigation, but as a practical matter, they let you look at everything,” said a former federal prosecutor who, like many interviewed for this article, spoke on the condition on anonymity because the FBI inquiry is continuing.
FBI agents can then roam through every corner of the account as if it were their own.
The capability to scour e-mail accounts has expanded the bureau’s investigative power dramatically, even in crimes previously seen as difficult to prosecute. For example, officials said, the ability to reconstruct communications between reporters and their sources helps explain why the Obama administration has been able to bring more leak prosecutions than all of its predecessors combined.
E-mail searches vary in scope and technique, from scanning contents for key words “to literally going through and opening every file and looking at what it says,” a former Justice Department official said.
Law enforcement officials said the FBI never sought access to Allen’s computer or accounts. It’s unclear whether it did so with Petraeus. But through Kelley and Broadwell, the bureau had amassed an enormous amount of data on the two men — including sexually explicit e-mails between Petraeus and Broadwell and questionable communications between Allen and Kelley.
Petraeus and Broadwell had tried to conceal their communications by typing drafts of messages, hitting “save” but not “send,” and then sharing passwords that provided access to the drafts. But experts said that ruse would have posed no obstacle for the FBI, because agents had full access to the e-mail accounts.
As they pore over data, FBI agents are not supposed to search for key words unrelated to the warrant under which the data were obtained. But if they are simply reading through document after document, they can pursue new leads that surface.
“Most times, if you found evidence of a second crime, you would stop and go back and get a second warrant” to avoid a courtroom fight over admissibility of evidence, a former prosecutor said. But in practical terms, there is no limit on the number of investigations that access to an e-mail account may spawn.
‘Because of who it was’
There is nothing illegal about the Petraeus-Broadwell affair under federal law. Were it not for Petraeus’s prominent position, the probe might have ended with no consequence. But because of his job — and the concern that intelligence officers caught in compromising positions could be susceptible to blackmail — the probe wasn’t shut down.
“If this had all started involving someone who was not the director of the CIA . . . they would have ignored it,” said David Sobel, senior counsel for the Electronic Frontier Foundation, a privacy group. “A bell went off because of who it was.”
That consideration triggered a cascade of additional quandaries for the Justice Department, including whether and when to notify Congress and the White House. The FBI finally did so on election night, Nov. 6, when Deputy Director Sean Joyce called Petraeus’s boss, Director of National Intelligence James R. Clapper Jr.
After being confronted by Clapper, Petraeus agreed to resign.
President Obama said last week that there was “no evidence at this point, from what I’ve seen, that classified information was disclosed that in any way would have had a negative impact on our national security.”
But the data assembled on Allen and Petraeus continue to reverberate. The FBI turned over its stockpile of material on Allen — said to contain as many as 30,000 pages of e-mail transcripts — to the Defense Department, prompting the Pentagon inspector general to start an investigation.
The CIA has also launched an inspector general investigation into Petraeus and his 14-month tenure at the agency, seeking to determine, among other things, whether he used the perks of the position to enable his affair with Broadwell.
If it follows its own protocols, the FBI will hold on to the data for decades. Former officials said the bureau retains records for 20 years for closed criminal investigations, and 30 years for closed national security probes.
Sari Horwitz and Julie Tate contributed to this report.