The case that ended up ensnaring CIA director David Petraeus FBI was started by the FBI in June with a collection of five e-mails, a few hundred kilobytes of data at most. By the time the probe exploded into public view earlier this month, says the Washington Post, the FBI was sitting on a mountain of data containing the private communications and intimate secrets of a CIA director and a U.S. war commander. What the bureau didn’t have is evidence of a crime. What it means for privacy and national security has caused what the Post calls "a queasy new understanding of the FBI's comprehensive access to the digitigal trails left by even top officials."
The trail cut across a seemingly vast territory with no clear indication of any boundaries the FBI imposed on itself. A criminal inquiry into e-mail harassment morphed into a national security probe of whether Petraeus and the secrets he guarded were at risk. After uncovering an extramarital affair, investigators shifted to the issue of whether Petraeus was guilty of a security breach. When none of those paths bore results, investigators settled on the target they are scrutinizing now: Paula Broadwell, Petraeus' biographer and mistress, and what she was doing with a cache of classified but apparently inconsequential files. On Capitol Hill, the case has drawn references to the era of J. Edgar Hoover, who was notorious for digging up dirt on Washington’s elite long before the invention of e-mail and the Internet.