The saga began to unravel with threatening e-mails that were sent to Jill Kelley, a socialite in Tampa, Fla., and a close friend of the Petraeus family. She became alarmed at these anonymous missives telling her to stay away from Mr. Petraeus, a retired four-star general.
So Ms. Kelley contacted a good friend at the FBI, Frederick Humphries, who set the investigation in motion. The agency traced the e-mails back to Paula Broadwell, Petraeus’s biographer. Investigators then found intimate e-mails between Ms. Broadwell and Petraeus, who resigned his post at the Central Intelligence Agency on Nov. 9 because of the burgeoning scandal.