Mustafa Ahmed al Hawsawi was the al Qaeda treasurer who bankrolled the 9/11 hijackers. He sent cash to lead hijacker Mohammed Atta through bank accounts in Dubai and the United Arab Emirates (UAE). He also helped finance the activities of Zacarias Moussaoui, the so-called “20th hijacker.” Investigators found al Hawsawi’s phone number on a Federal Express package sent by Atta (in early September 2001) from Florida to the UAE. The same number was also used as a contact point for a wire transfer to Ramzi Binalshibh, who has admitted a role in planning the 9/11 attacks.

Al Hawsawi was captured, along with terrorist mastermind Khalid Shaikh Mohammed, by U.S. forces in Pakistan in March 2003. In 2006 al Hawsawi was one of 14 key al Qaeda operatives transferred from CIA custody to the U.S. military prison at Guantanamo Bay, Cuba.