The FBI considered it a criminal matter, not one of intelligence, according to law enforcement sources.
The sources said agents followed department guidelines that generally bar sharing information about developing criminal investigations. The FBI is also aware of its history under former director J. Edgar Hoover of playing politics and digging into the lives of public figures. As one official said, the rules are designed to protect people (both private and elected officials) when negative information about them arises in the course of a criminal investigation that is not a crime.
The FBI’s focus was on whether laws were broken, in this case whether federal cyber-harassment statutes were violated. The sources emphasized that Petraeus himself was never the focus of the investigation, nor did it turn up evidence he broke any law.
The focus was on his biographer, Paula Broadwell, with whom he had the affair that ended with his resignation as CIA director last week.