▸ Khalid Sheikh Mohammed, who admitted to interrogators that he was the mastermind of the attacks. Born in Pakistan, he allegedly proposed the concept to Osama bin Laden as early as 1996, obtained funding, oversaw the operation, and trained the hijackers in Afghanistan and Pakistan.
▸ Waleed bin Attash, a Yemeni better known as Khallad, allegedly ran an Al Qaeda training camp in Afghanistan, where two of the 19 hijackers were trained, and is believed to have been bin Laden’s bodyguard. Authorities say bin Laden selected him as a hijacker, but he was detained in Yemen in early 2001.