Mystery solved. Frederick Humpries is the FBI agent who helped start the investigation that led to this whole Petraeus affair scandal, but, more importantly, he's also the FBI agent who emailed a shirtless picture of himself to Jill Kelley.

But according to Lawrence Berger, the general counsel for the Federal Law Enforcement Officers Association, there's a reasonable explanation for the shirtless photo.

"That picture was sent years before Ms. Kelley contacted him about this, and it was sent as part of a larger context of what I would call social relations in which the families would exchange numerous photos of each other," Mr. Berger said.

The photo was sent as a "joke" and was of Mr. Humphries "posing with a couple of dummies." Mr. Berger said the picture was not sexual in nature.

Sure. Moving on.

Berger also said that Humphries only received and passed on information from Kelley and was never involved in the actual investigation. A law enforcement official told the New York Times that Humphries's actions were under review but that he hadn't been suspended or reprimanded.

In addition to taking shirtless pictures with dummies, Humphries is a "hard-charging" veteran of the FBI who "used his command of French" to help build a case against Ahmed Ressam, the so-called Millenium Bomber who tried to set off a bomb at Los Angeles International Airport in 1999.

If the whole "command of French" part makes you question Humphries toughness, there's also this:

In May 2010, after he had moved to the Tampa field office, Mr. Humphries was attacked outside the gate of MacDill Air Force Base by a disturbed knife-wielding man. He fatally shot the man, and the shooting was later ruled to be an appropriate use of force, according to bureau records and colleagues.

So, it may be a good idea to watch the shirtless picture jokes around him. Speaking of which, if you have that picture let us know.

[Image via AP]