New revelations of an FBI agent being involved in the murky saga of alleged affair between General David Petraeus, former head of the CIA, and his biographer Paula Broadwell, rocked Washington on Thursday.

The latest twist in the case came as it was revealed that Frederick Humphries II, a “veteran terrorism investigator” at the FBI was the man who exposed the Petraeus-Broadwell relationship to members of the U.S. Congress, though Mr. Humphries was banned from pursuing the case; and is being investigated for sending shirtless photographs of himself to another key figure in the case, Jill Kelley.

Ms. Kelley, said to be a volunteer who organised social events for military personnel in Tampa, Florida, was the alleged recipient of “harassing emails” from Ms. Broadwell. A complaint about the mails had spurred the FBI’s initial probe into the affair.

This week The New York Times revealed Mr. Humphries’ name, adding that his colleagues described him as having “conservative political views and a reputation for aggressiveness”, and also as a “hard-charging veteran who helped investigate the foiled millennium terrorist plot in 1999”.

Additionally, reports suggested that Mr. Humphries was involved in a number of high-profile terrorism investigations including the case of Abu Hamza al-Masri, recently extradited from the U.K. Mr. Humphries was also said to have averted a terrorist bombing of Los Angeles International Airport after shooting a man who attacked him with a knife at the gates of MacDill Air Force Base in Tampa.

The Obama administration appeared to be stunned over the weekend when news emerged of the FBI’s investigation into emails that General Petraeus, a four-star General, who led the U.S. campaigns in Iraq and Afghanistan, exchanged with Ms. Broadwell, revealing his affair with her. However, the federal inquiry also unexpectedly trapped a second, senior military figure in the expanding net of amorous allegations — General John Allen, currently commander of the Afghan war. General Allen was said to have traded “flirtatious emails” with Ms. Kelley, prompting an investigation into whether he had passed on any classified or sensitive information to her. The identity of Mr. Humphries was revealed even as Reuters News Agency quoted unnamed officials admitting that a computer used by Ms. Broadwell, “contained substantial classified information that should have been stored under more secure conditions”, and questions about how Ms. Broadwell got that information were “significant enough to warrant a continuing investigation”.