Federal officials have said in recent months that there is no death chamber at the detention camp at the United States naval base at Guantánamo Bay, Cuba, and that they knew of no specific plans for how a death sentence would be carried out.

The military justice system, which does not govern the Guantánamo cases, provides for execution by lethal injection in death sentence convictions. But the United States military has rarely executed a prisoner in recent times.

The last military execution was in 1961, when an Army private, John A. Bennett, was hanged after being convicted of rape and attempted murder. Currently, there are six service members appealing military death sentences, according to a recently published article by a lawyer who specializes in military capital cases, Dwight H. Sullivan, a former chief military defense lawyer at Guántanamo.

One official who had been briefed on the war-crimes case said the charges were expected to be lodged against six detainees held at Guantánamo, including Mr. Mohammed, who is said to have presented the idea of an airliner attack on the United States to Osama bin Laden in 1999 and then coordinated its planning.

The official identified the others to be charged as Mohammed al-Qahtani, the man officials have labeled the 20th hijacker; Ramzi bin al-Shibh, said to have been the main intermediary between the hijackers and leaders of Al Qaeda; Ali Abd al-Aziz Ali, known as Ammar al-Baluchi, a nephew of Mr. Mohammed, who has been identified as Mr. Mohammed’s lieutenant for the 2001 operation; Mr. al-Baluchi’s assistant, Mustafa Ahmed al-Hawsawi; and Walid bin Attash, a detainee known as Khallad, who investigators say selected and trained some of the hijackers.

Relatives of the Sept. 11 victims have expressed differing views of potential death sentences, with some arguing that it would accomplish little other than martyring men for whom martyrdom may be viewed as a reward.

But on Sunday, Debra Burlingame, whose brother Charles F. Burlingame III was the pilot of the hijacked American Airlines Flight 77 that was crashed into the Pentagon, said she would approve of an effort by prosecutors to seek the execution of men she blames for killing her brother. Ms. Burlingame said such a case could help refocus the public’s attention on what she called the calculated brutality of the attacks, which she said has been largely forgotten.