The official told The New York Times the emails with Kelley might violate Defense Department policy and regulations or military law. While the two exchanged several hundred messages, only some "bear a fair amount of scrutiny."
Kelley had an unofficial but close relationship with members of the military at MacDill Air Force Base in Tampa, the headquarters of Central Command, becoming friendly with Allen and CIA Director David Petraeus, who resigned this month. Her email exchanges with Allen came to light when she complained of receiving harassing emails that turned out to be from Paula Broadwell, Petraeus' biographer and one-time lover.
The investigation has delayed Allen's appointment as NATO commander in Europe. While the official said as many as 15 investigators are working seven days a week on the Allen investigation, it could still take some time.
The defense official said the FBI gave the Defense Department the emails.
"They just forwarded the evidence," he told the Times. "People have to go through and decide if they fit one of three potential violations."