Central Intelligence Agency Director David Petraeus resigned after a probe into whether someone else was using his email led to the discovery that he was having an extramarital affair

CIA Director David Petraeus resigned as head of the intelligence agency, saying he "showed extremely poor judgment" by engaging in an extramarital affair

The computer-security investigation—which raised questions about a potential compromise to national security—points to one reason Mr. Petraeus and the White House decided he couldn't remain in the senior intelligence position. An extramarital affair has significant implications for an official in a highly sensitive post, because it can open an official to blackmail.