For most Washington insiders, the most surprising aspect of General David Petraeus' spectacular downfall is not the moral reprobation attached to adultery.  It is that a presumed professional named to head the Central Intelligence Agency could leave himself so blatantly exposed, and do it over Gmail. What was he thinking?  Clearly, he wasn't.

As the Wall Street Journal reports in its Monday (November 12, 2012) edition, Petraeus naively thought that opening a Gmail account under an alias would keep his correspondence in the extramarital affair secret. That was actually his second mistake.  The first was having the affair to begin with.  Adulterous affairs are nearly always bad news, but the problem in Petraeus' case took on an added dimension. The moment he engaged in illicit behavior with a woman outside his marriage, he became hostage to that woman's behavior and consequently to her idiosyncricies.  In short, she automatically became the weak link in his defenses. As head of the CIA, Petraeus needed to be more secure than anyone else, and the woman he had entrusted with his future turned into something of an unguided missile.  In a profession in which extortion and blackmail are tools of the trade, he had lost control. 

David Petraeus (left), Scott Kelley, Jill Kelley, Holly (Hollister) Petraeus

There seems to be no question that Petraeus's biographer  Paula Broadwell was genuinely smitten with him, but what Petraeus hadn't counted on was jealousy. 

When harassing emails began arriving in the in-box of Jill Kelley,  an attractive social planner at MacDill Air Force Base last May, the FBI entered the picture.  Kelley and her husband Scott were longtime family friends of the Petraeus family. The emails were not signed, but the FBI was able to track the metadata--the address routing  information at the top of the email heading--to a joint Gmail account belonging to Paula Broadwell and her husband.  That was enough for the FBI to begin looking at all of Paula Broadwell's emails and to find unauthorized classified information among her messages. As it turned out, the classified information did not come from Petraeus. It was simply a bit of added spice that gave more urgency to the FBI's search.

When the ongoing sexual liaison also surfaced, the FBI began looking for the person using the phony identity that Petraeus had thought would guarantee his anonymity. As it turned out, the alias didn't really guarantee anything.  It did not take long for the FBI to track the actual traffic back to a physical computer and to discover that the computer had been used by Petraeus.  The game was up.  

Luckily, no classified information appears to have been seriously compromised, and in fact, Petraeus was lucky that the FBI got there first. A hostile and less genteel organization--one more like the CIA-- might not have been as forgiving.   The ultimate question, and the one that President Obama had to resolve, was how  anyone in as sensitive a position as Petraeus could have been so oblivious and still be trusted with the guarding America's security against all enemies, foreign and domestic.  The answer is that he couldn't.