David Petraeus and Paula Broadwell reportedly started their affair shortly after Petraeus began heading the CIA in September 2011.

AP Photo/ISAF

he Senate Intelligence Committee will investigate why the FBI failed to immediately notify the White House and Congress when it discovered that David Petraeus, who resigned his CIA director position on Friday, had been involved in an extramarital affair. The FBI began its investigation, reportedly sometime this past summer, after a Florida woman, identified as Jill Kelley, a friend of Petraeus and his wife, filed a complaint that she had received threatening emails warning her to stay away from Petraeus. The emails, which were traced back to Paula Broadwell — the woman with whom Petraeus had the affair and who authored his official biography — included sexually explicit messages sent from Petraeus' personal account. After the FBI verified that the emails from Petraeus were not fabricated, they confronted him and Broadwell, who both admitted to the affair. The FBI says it did not inform Congress of the investigation because it was a criminal investigation into the allegedly threatening emails. Lawmakers weren't completely in the dark, about the probe, though, as House Minority Leader Eric Cantor (R-Va.) was contacted in late October by an FBI employee who informed him of the allegations. Sen. Dianne Feinstein (D-Calif.), who has led the charge against the FBI, says it's possible that Petraeus could be called to testify before the committee.