U.S. General David Petraeus
U.S. General David Petraeus testifies at his Senate Armed Services Committee confirmation hearing to become commander of U.S. forces in Afghanistan on Capitol Hill in Washington June 29, 2010. REUTERS

A shirtless photo that FBI agent Fred Humphries sent to Tampa socialite Jill Kelley, the alleged second “other woman” in the David Petraeus affair, was meant as a joke and was not intended to be sexual, according to the agent, ABCNews.com reported.

Humphries' involvement in the sex scandal was revealed when he was identified on Wednesday as the “whistleblower” in the federal investigation into Petraeus’ affair with his biographer, Paula Broadwell. Humphries, 47, is a supervisor in the Joint Terrorism Task Force in Tampa and a longtime personal friend of Kelley, who serves as a “social liaison” at MacDill Air Force Base in Tampa.

When Kelley complained to Humphries that she had been receiving harassing, anonymous emails that accused her of being inappropriately flirtatious with Petraeus, Humphries set off a chain of events that led to a federal investigation that eventually uncovered the ex-CIA director’s affair with Broadwell. Sources have speculated that Broadwell was jealous of the attention Kelley was getting from Petraeus, and Broadwell ordered her to “back off” from “my man.”

Broadwell also sent anonymous emails, some under the alias “KelleyPatrol,” to other people, including Gen. John R. Allen, while he was serving overseas in Afghanistan, urging them to stay away from Kelley and suggesting that she was “trouble.”

"There was absolutely no romantic involvement or relationship whatsoever between Agent Humphries and Jill Kelley," said Humphries’s attorney, Lawrence Berger, in an interview with ABC News on Wednesday.

Humphries identified a photograph published by the Seattle Times, in which the FBI agent poses in between two shooting range dummies, who bear an uncanny resemblance to him. Berger said that the photo was just a “joke picture” and had been sent to Kelley and her husband, along with many other people, including a reporter for the Seattle Times, before Kelley had begun receiving the emails.

One former colleague described Humphries as “a passionate kind of guy.”

“He’s kind of an obsessive type. If he locked his teeth onto something, he’d be a bulldog,” the colleague said.

Berger also denied that his client was the “whistleblower” in the investigation, as several media outlets have reported, but he would not comment on the New York Times’ claim that Humphries had approached Rep. Dave Reichart with concerns that the FBI had halted their investigation of Petraeus’ extramarital affair for political reasons.