Frederick W Humphries II, is a veteran terrorism investigator and helped foil the terrorist plot in 1999.

Humphries is known among his colleagues as being relentless in his pursuit of wrongdoings. Humphries pursued Petraeus as he believed he was breaching security.

Humphries colleagues at the CIA believed that his investigation into Petraeus was unjustified, so he took the matter to Congressional Republicans.

“He’s kind of an obsessive type. If he locked his teeth onto something, he’d be a bulldog,” said one colleague about Humphries, as reported in the New York Times.

The original complaint came from Jill Kelly, from Tampa. Who took ‘flirty’ emails to the agent Humphries. “The agent said: ‘This is serious. They seem to know the comings and goings of a couple of generals,’ ” explained a spokesman for Kelly.

Through further investigations into emails it emerged that Petraeus and his biographer, Paula Broadwell, were having an affair.
Petraeus offered his resignation to Obama on Thursday. The resignation was published on Friday. Petraeus explained it was due to ‘personal reasons’.

Pictures: Getty