Mohammed in the past expressed an interest in pleading guilty so that he could be swiftly executed, but there have been indications that he and the four others plan to fight the charges this time. The case is likely to last a couple of years, followed by a lengthy appeals process. This would provide Mohammed, who seems to relish the spotlight, a stage from which to issue various pronouncements.
The case has generated a great deal of interest, with more than 50 American and foreign journalists traveling to Cuba, as well as observers from major human rights groups.
The five defendants will probably indicate whether they wish to keep the military and civilian counsel that have been retained for them. In the earlier trial, Mohammed had insisted on representing himself, a wish that a previous judge granted to him and two other defendants, Walid bin Attash, a Yemeni, and Abd al Aziz Ali, a Pakistani.
The ability of two other defendants — Ramzi Binalshibh, a Yemeni, and Mustafa Ahmed al Hawsawi, a Saudi — to represent themselves was still under review when proceedings in the case were suspended in January 2009.
Almost immediately after coming into office, President Obama halted proceedings at Guantanamo as part of his goal to close the detention center. His administration hoped to move the Sept. 11 case to New York, but that effort collapsed in the face of local and congressional opposition.
In April 2011, Attorney General Eric H. Holder Jr. announced that the case would be returned to the military. Prosecutors renewed the charges against Mohammed last month, and a senior Pentagon official referred the case for trial.
Because of the complexity of trying five defendants simultaneously on capital charges, the selection of a jury of military officers and opening arguments could be a year or more away.
Staff writer Julie Tate contributed to this report.