The asymmetry was disturbing. There were five hijackers on the plane that crashed into the North Tower, five on the flight that brought down the South Tower, and five on the one that plowed into the Pentagon. But there were only four on United 93, which crashed in an empty field in western Pennsylvania. Was there supposed to be a fifth man on that flight too? Was he still at large? So when the news broke in the days after 9/11 that, nearly a month before the attacks, U.S. immigration officials in Minnesota had arrested and continued to hold Zacarias Moussaoui—a French-Moroccan man with jihadist ties who’d come to the States to attend flight-training school—it seemed as if at least one mystery had been solved. In Moussaoui, we had found the twentieth hijacker.
But Moussaoui’s incompetence soon proved to be so great that it became difficult to believe Al Qaeda would have ever entrusted him to mail a postcard, much less pilot a plane. He dropped out of one flight school. He aroused suspicions at another by reportedly saying he wanted to learn how to fly a 747 but had no interest in taking off or landing. Representing himself for part of his trial (his court-appointed attorneys were “bloodsuckers” and “the death team”), he denied he was part of the 9/11 plot before later pleading guilty to the charges. By the time he was sentenced to life in prison, in 2006, the captured 9/11 mastermind Khalid Shaikh Mohammed had told American interrogators that Moussaoui wasn’t part of that terrorist plot but another one. And not long after Moussaoui arrived at the federal supermax prison in Colorado, an audiotape believed to be from bin Laden surfaced, stating, “I am the one in charge of the nineteen brothers, and I never assigned brother Zacarias to be with them in that mission … [H]e wasn’t No. 20 in the group.”
So was there a No. 20, after all? If so, who was he? According to the 9/11 Commission, there were at least nine and possibly ten men, in addition to the nineteen on the planes, whom bin Laden recruited to participate in the attacks, but only one of those men appears to have come close to joining the nineteen (the others either weren’t able to enter the U.S. or backed out) [T4 ].
In August 2001, a little more than a month before the attacks, a Saudi man in his early twenties named Mohammed Mani Ahmed al-Qahtani flew from Dubai via London to Orlando. According to Mustafa al-Hawsawi, one of the 9/11 financiers, Qahtani was “the last one” to “complete the group,” and Mohamed Atta himself had driven to the Orlando airport to meet him. But when Qahtani—who traveled on a one-way ticket and carried only $2,800—tried to go through Customs, a border official suspected he might try to immigrate illegally and sent him back to Dubai.
The following December, Qahtani was captured by Pakistani forces as he was retreating from the battle of Tora Bora. He was later turned over to American officials and sent to Guantánamo, where FBI agents reportedly ascertained that he was indeed supposed to be the twentieth hijacker. In 2008, military prosecutors announced that Qahtani was being charged with war crimes and murder. But in January 2009, six days before George W. Bush left office, a top administration official announced the charges against Qahtani would be dropped on the grounds that the evidence was tainted because he’d been tortured. Military interrogators subjected him to, among other things, sleep deprivation and isolation. He remains in detention at Gitmo. In 2005, lawyers from the Center for Constitutional Rights filed a habeas petition on Qahtani’s behalf. The case, which was originally called Qahtani v. Bush, is still pending. (It’s now called Qahtani v. Obama.) According to an October 2008 “Detainee Assessment” released by WikiLeaks earlier this year, Qahtani is “in good health” and remains a “high risk, as he is likely to pose a threat to the U.S., its interests, and allies.”