Accused 9/11 mastermind Khalid Sheikh Mohammad and two other men charged with plotting the Sept. 11, 2001, terror attacks by al-Qaeda have agreed to plead guilty in the military commissions process, the Pentagon said Wednesday.

The terms of the plea deals for the three men, who have been in custody since 2003, were not released, but they are expected to plead guilty to some charges, and potentially avoid death sentences as a result.

The Office of Military Commission said the defendants will enter their pleas as early as next week at the U.S. military base at Guantanamo Bay, Cuba.

In addition to Mohammed, the other men expected to plead guilty are Walid Muhammad Salih Mubarak Bin 'Attash, and Mustafa Ahmed Adam al Hawsawi.

The New York Times reported that the chief prosecutor in the case, Rear Admiral Aaron Rugh, in a letter to 9/11 victim family members, had written, "In exchange for the removal of the death penalty as a possible punishment, these three accused have agreed to plead guilty to all of the charged offenses, including the murder of the 2,976 people listed in the charge sheet."

The prosecution against the men and other defendants being held at Guantanamo Bay has dragged on for more than 16 years. The long delay is in large part the result of legal disputes over the admissibility of evidence obtained from the defendants while they were tortured in CIA detention sites.

Almost 3,000 people were killed in the Sept. 11 attacks, when four teams of terrorists hijacked four airliners in the United States, flying two of them into the Twin Towers at the World Trade Center in New York City, and the third plane into the Pentagon building.

The fourth hijacked plane crashed in a field near Shanksville, Pennsylvania, after passengers tried to break into the cockpit.

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