Mueller and his deputy, Sean Joyce, have met privately with lawmakers to defend how the inquiry was handled. Holder said on Thursday that law enforcement officials did not inform the president and Congress about the probe because it did not uncover any threat to national security.
In one such incident, a woman told the AP that her ex-boyfriend posted online an intimate video and nude photos of her with her name and email address, and she complained to the FBI. Speaking on condition of anonymity because she feared personal and professional repercussions, the woman said she had been deluged with offensive messages from strangers who viewed the photos and video. Her personal and professional reputation had been ruined. She changed her name.
The FBI's advice to her: hire a lawyer.
But the FBI considered Kelley's complaint significant. And for good reason, said David Laufman, a former federal prosecutor who handled national security cases. "Most cases aren't going to get this level of attention or resources," he said. "But most cases don't involve the incumbent director of the CIA or the head of U.S. military forces in Afghanistan."
Kelley contacted an FBI agent in Tampa she had met years earlier. The bureau believed the emails were serious because they suggested the mysterious sender knew about upcoming meetings of the CIA director and a Marine Corps general.
Agents examined the digital fingerprints that emails leave behind and eventually determined Broadwell had sent the messages from an account set up with a fictitious name. As the agents looked further, they came across a private Gmail account that used an alias name. It turned out to be Petraeus'. The contents of several of the exchanges between Petraeus and Broadwell indicated they were having an affair. A search of Broadwell's computers also found classified documents.
Most cyberstalking allegations are handled by state and local law enforcement organizations, said Michelle Garcia, director of the Stalking Resource Center at the National Center for Victims of Crime. "Given the variety of crimes that the FBI is responsible for addressing, I think often some of the stalking ones don't elevate to the top of the priority list," she said.
State police agencies have little contact with the FBI in responding to cyberstalking cases, Garcia said. "In our work with local law enforcement, very rarely do they talk about working with federal authorities on these cases."
The Petraeus case has drawn attention to how easy it is for the government to examine emails and computer files if they believe a law was broken. The FBI and other investigating agencies armed with subpoenas and warrants routinely gain access to email accounts offered by Google, Yahoo and other Internet providers.
Civil liberties groups have criticized the FBI for pursuing the investigation of the emails to Kelley because there is no indication the messages contained any threatening language or classified information. The episode underscores the need to strengthen the legal protections for electronic communications, according to the American Civil Liberties Union.
Federal agencies can obtain a substantial amount of information about the online activities of an individual without getting a warrant from a judge. A subpoena approved by a federal prosecutor is usually sufficient to get access to stored emails and login data.
"These are invasive powers that need to have a check against overuse and abuse," said Chris Soghoian, a senior policy analyst at the ACLU. "And that check should be a judge."