By DEVLIN BARRETT, EVAN PEREZ and SIOBHAN GORMANWASHINGTON—A federal agent who launched the investigation that ultimately led to the resignation of Central Intelligence Agency chief David Petraeus was barred from taking part in the case over the summer due to superiors' concerns that he was personally involved in the case, according to officials familiar with the probe.
After being blocked from the case, the agent continued to press the matter, relaying his concerns to a member of Congress, the officials said.
New details about how the Federal Bureau of Investigation handled the case suggest that even as the bureau delved into Mr. Petraeus's personal life, the agency had to address conduct by its own agent—who allegedly sent shirtless photos of himself to a woman involved in the case prior to the investigation.
FBI officials declined to identify the agent, so he couldn't be reached to give his side of the story. The agent is now under investigation by the Office of Professional Responsibility, the internal-affairs arm of the FBI, according to two officials familiar with the matter.
The revelations address how the investigation first began and ultimately led to Mr. Petraeus's downfall as director of the CIA. The new developments also raise questions about the role played by the FBI and the adequacy of notification to administration and congressional leaders about the scandal.
The FBI agent who started the case was a friend of Jill Kelley, the Tampa woman who received harassing, anonymous emails that led to the probe, according to officials. Ms. Kelley, a volunteer who organizes social events for military personnel in the Tampa area, complained in May about the emails to a friend who is an FBI agent. That agent referred it to a cyber crimes unit, which opened an investigation.
However, supervisors soon became concerned that the initial agent might have grown obsessed with the matter, and prohibited him from any role in the investigation, according to the officials.
One official said the agent in question sent shirtless photos to Ms. Kelley well before the email investigation began, and FBI officials only became aware of them some time later. Eventually, supervisors told the agent he was to have nothing to do with the case, though he never had a formal role in the investigation, the official said.