Two panel members served as senior officers in the late 2001 U.S. invasion of Afghanistan - one on the ground and another at Central Command headquarters in Tampa - overseeing operations that captured thousands of detainees, toppled the Taliban and transferred hundreds to this Navy base in southeastern Cuba.

Hamdan was among them.

A third member, a Marine colonel, revealed that a member of his reserve regiment was a firefighter killed in the World Trade Center attack. He attended the firefighter's funeral and went to ground zero two weeks after the attack.

"It was a sad sight, a lot of destruction there. . . . I would imagine that everyone who saw it was angry, " said Col. Jack K. Sparks Jr., chief of staff of the Marine Corps Combat Development Command.

"It would seem to me that somewhere in the officers corps we can pull someone who was not an intelligence officer in Afghanistan, was not involved in detainee operations, who did not go to the 9/11 site two weeks afterwards, " Swift said. "Because it's not a random drawing of your friends and neighbors, it should be cleaner. It should be squeaky clean."

The alternate, Army Lt. Col. Curt S. Cooper, admitted under questioning that he had not read the Geneva Conventions that protect the rights of prisoners of war.

"Do you know what the Geneva Convention is, sir?" Swift asked.

"Not specifically, no sir. That's being honest, " Cooper replied.

Also on the panel are Air Force Lt. Col. Timothy Toomey, who served as an intelligence officer for three months in Afghanistan; Marine Col. R. Thomas Bright, who ran the Centcom nerve center that organized detainee flights from Afghanistan to Guantánamo; and Air Force Col. Christopher Bogdan, whose seat was not challenged.

The trials continue today with a preliminary hearing for David Hicks, 29, of Adelaide, Australia, a one-time Outback cowboy who ran away from home and converted to Islam. His father arrived at the base Tuesday to see his son for the first time in years.

TIGHT SECURITY

The session was held amid tight security. Dogs sniffed through the courtroom and security officers turned it into a virtual safe, impenetrable to Cuban electronic sensors routinely aimed at the 101-year-old Navy base.

American Civil Liberties Union Executive Director Anthony Romero called the session "window dressing" for a wider problem - the continued interrogation and detention without charge of about 580 other men from 34 nations.

"Even though we are witnessing four men in commissions this week, there are 581 other individuals who aren't part of this process. It's not clear what will happen to them at all."

THE MILITARY COMMISSIONS

* Five U.S. military officers will rule on the guilt or innocence of foreigners held at Guantánamo who are accused of war crimes.

* One is Army Col. Peter Brownback III, a retired military judge called back into service.

* Brownback has the power to close the trial to shield classified and secret information from public view, and to retroactively declare information heard in open court "protected, " banning journalists from reporting it.

* By design, the other four commission members do not have legal backgrounds. They are three colonels and a lieutenant colonel, all from either the Air Force or Marines.