David Petraeus and Paula Broadwell - AP
(USA TODAY) - Paula Broadwell, ex-mistress of disgraced former CIA chief David Petraeus, could have used several different methods to hide her identity if in fact she sent anonymous, threatening emails to Tampa socialite Jill Kelley, experts say.
But Shawn Henry, who retired in March as the FBI's executive assistant director in charge of all civil and criminal cyber investigation worldwide, says the FBI had many techniques available to trace the communications.
"Somewhere along the way, her IP address was captured," Henry said.
Someone trying to remain anonymous can hide emails by routing them through different servers and using public computers that don't keep activity logs, he said. Broadwell may have thought she had done everything to hide her tracks, but often people make mistakes, leaving their emails traceable by investigators, he said.
The Associated Press, citing a law enforcement source who declined to be identified, reported that Petraeus and Broadwell apparently used a "dropbox" to conceal their email traffic.
Rather than transmitting emails to the other's inbox, they composed at least some messages and left them in a draft folder or in an electronic dropbox, AP said. Then the other person could log onto the same account and read the draft emails, avoiding the creation of an email trail that might be easier to trace.
The scandal has widened, with the top U.S. commander in Afghanistan under investigation for alleged "inappropriate communications" with Kelley.
Defense Secretary Leon Panetta revealed that the Pentagon had begun an internal investigation into thousands of pages of emails from Gen. John Allen to Kelley. A senior Defense official described the emails as "flirtatious."
It's not clear if there was an effort to hide that email trail, and Allen has denied wrongdoing.
"Every circumstance is going to be a little different," Henry told USA TODAY. "It may have been relatively easy or difficult for FBI investigators. It depends on how hard someone tried to hide their transactions. And they can try really hard and then make a mistake."
The FBI would deploy its resources to uncover the sender of an anonymous email depending on the credibility of the suspicious email, the severity of the threat and the target, said Henry, who worked at the FBI for 24 years and is now president of CrowdStrike Services, a cyber security firm.
"You absolutely would have to look at the totality of the situation," he said. "There are a whole host of things you factor in."
Before pursuing any investigation, FBI agents would seek an opinion from a prosecutor to determine whether it's possible that laws had been broken, he said.
"We would rarely pursue an investigation without going to an independent prosecutor," he said. "These types of cases are not atypical. They happen relatively frequently."
Usually, the cases are worked with local law enforcement, Henry said.
"If the Bureau decided to work it, it would indicate to me that there was more to it," Henry said. "If the target is named and it's a high level official, that would raise people's attention. It indicates to me that there was more to this, not just a random email."
How long such an investigation takes would vary with the number of leads that need to be run down and the complexity of the cyber trail, he said.
"In these types of cases, there are many complexities," Henry said. "If they discovered the director of CIA is involved you want to make sure you get all the facts because it's going to impact a lot of other people. The bureau would want to collect all of the evidence and really fully flesh this out before it went public."