Last December, Mike McConnell, the outgoing director of national intelligence, said that Osama bin Laden’s son, Saad bin Laden “has left Iran” and is “probably in Pakistan.” Yesterday came the news that Saad bin Laden is dead, that even the CIA is not certain and the Taliban is denying the report. He was reportedly killed in one of the CIA’s Predator drone attacks in Taliban-controlled tribal areas of Pakistan.

It’s a mystery worthy of a spy novel.

In 2001, fleeing the US invasion of Afghanistan, Saad bin Laden and a small number of other top Al Qaeda officials ended up in Iran, though the vast majority of Taliban and AQ officials headed south and east into Pakistan. The choice of Iran was a curious one, since the anti-Taliban force in Afghanistan, the Northern Alliance, was supported by Iran, Iran had nearly gone to war with the Taliban-controlled Afghanistan in the past, and Al Qaeda’s militant Sunni fundamentalist ideology put it at odds with Iran’s Shiite version of political Islam.

Exactly what Saad bin Laden and his allies were doing in Iran is also a mystery. Most analysts that I’ve spoken with over the years say that they believe the AQ leaders were under close watch and house arrest, and that they had no operational capabilities. Despite claims in some quarters that the Iranian-based AQ group, including Saad bin Laden, were responsible for directing acts of terrorism aimed at Saudi Arabia and the Gulf, no real evidence emerged to back up that theory. Nevertheless, during the Bush administration, officials — including Nick Burns, a top State Department official — often charged Iran with harboring Al Qaeda, adding that to the list of anti-Iran grievances that they piled up against Tehran. Yet it seemed extremely unlikely that Iran would expose itself to charges that it was cooperating with AQ. More likely, some analysts suggested, Iran was holding Saad bin Laden (who apparently stayed in Iran from 2001 to 2008) as a kind of bargaining chip, and that Tehran was willing to trade him and his comrades to the United States as part of a deal, perhaps involving the leaders of the anti-Iran Mujaheddin-e Khalq (MEK) that was based in Iraq and protected by US forces.

The Washington Post makes an explosive (and unsourced) charge in an offhand manner in its story today:

“In addition to his alleged involvement in a 2003 al-Qaeda bombing in Riyadh, Saudi Arabia, he also is said to have served as a link between the terrorist group and the Quds Force, an Iranian special operations group that has attacked U.S. troops in Iraq.”

Does the Quds Force, about which almost nothing is known, maintain a secret liaison with Al Qaeda? It might — stranger things have happened in the shadowy world of intelligence — but there’s precious little evidence that it does, certainly not enough for the Post to say that it “is said” that it does without providing detailed sourcing and some contrary opinion as well.

In contrast, the New York Times shies away from incendiary charges such as a Quds-AQ alliance, and it offers a different theory:

“Saad bin Laden was one of a number of Qaeda operatives detained inside Iran in recent years. American officials have long puzzled over the exact circumstances of their captivity, but they think that Iran was holding the militants in part as a deterrent against a Qaeda attack on Iranian soil.”

I’m not willing to give Iran and the Quds Force, which is an arm of the Iranian Revolutionary Guard Corps, a free pass. But it seems unlikely that Iran would need to use AQ for any real purpose, since it has plenty of operatives of its own to play with. (Hezbollah comes to mind.) Using AQ would expose Iran to a direct US assault, among other things, and then there’s that little matter of the ideological divide. (As the Times points out, Iran is more likely an AQ target than a sponsor!) But then there is this question: why, and how, did Saad bin Laden leave Iran for Pakistan last year? Did he escape? That seems preposterous. Did Iran let him go? If so, why? Did Tehran get tired of holding the hot potato? Was it a gesture to the United States? And then this question: Is Saad bin Laden really dead?