The Pentagon has dropped charges against a Saudi at Guantanamo who was alleged to have been the so-called "20th hijacker" in the Sept. 11 attacks, his U.S. military defense lawyer said Monday.

Mohammed al-Qahtani was one of six men charged by the military in February with murder and war crimes for their alleged roles in the 2001 attacks. Authorities say al-Qahtani missed out on taking part in the attacks because he was denied entry to the U.S. by an immigration agent.

But in reviewing the case, the convening authority for military commissions, Susan Crawford, decided to dismiss the charges against al-Qahtani and proceed with the arraignment for the other five, said Army Lt. Col. Bryan Broyles, the Saudi's military lawyer.

Officials previously said al-Qahtani had been subjected to a harsh interrogation authorized by former Defense Secretary Donald Rumsfeld.