(Updates with censorship question, hearing ends for the day)
* Pretrial hearings resume for five charged in 9/11 attacks
* Audio feed is mysteriously cut during hearing
* Defense wants secret CIA prisons preserved as evidence
By Jane Sutton
GUANTANAMO BAY U.S. NAVAL BASE, Cuba, Jan 28 (Reuters) - The sound was abruptly cut in the Guantanamo war crimes court on Monday, prompting the angry judge to question whether someone outside the room was censoring pretrial hearings for five men accused of plotting the Sept. 11 attacks on the United States in 2001.
In all hearings for the alleged al Qaeda operatives who were previously held in secret CIA prisons, a court security officer seated near the judge controls a button that muffles the audio feed to spectators when secret information is disclosed. A red light flashes and observers hear nothing but static.
The feed was cut when David Nevin, a lawyer for the alleged mastermind of the hijacked plane plot, Khalid Sheikh Mohammed, asked if the lawyers and judges needed to meet in closed session before considering a defense request.
When the feed was restored moments later, the judge, Army Colonel James Pohl, indicated it wasn't the court security officer who cut the sound in the proceedings formally known as military commissions.
"If some external body is turning things off, if someone is turning the commissions off under their own views of what things ought to be, with no reason or explanation, then we are going to have a little meeting about who turns that light on or off," Pohl said tersely.
He seemed to be addressing the prosecution team and told them that Nevin had merely referred to the caption of an unclassified document - one asking the judge to order that the secret CIA prisons where the defendants say they were tortured be preserved as evidence.
A short time later, the judge said he would meet in closed session with the lawyers and reopen the public part of the hearing on Tuesday. The episode enlivened the first day of a weeklong pretrial hearing in the military tribunal at the Guantanamo Bay U.S. Naval Base in Cuba.
Mohammed and his four co-defendants are accused of training and aiding the hijackers who slammed commercial jetliners into the World Trade Center in New York, the Pentagon and a Pennsylvania field on Sept. 11, 2001. They could be executed if convicted of charges that include terrorism, attacking civilians and murdering 2,976 people.
Under a program during the presidency of George W. Bush, the defendants were among the suspected al Qaeda captives who were moved across borders without judicial review and held and interrogated in secret CIA prisons overseas.
The CIA has acknowledged that Mohammed was subjected to the simulated drowning technique known as waterboarding. The defendants said they also were subjected to sleep deprivation, threats, and being chained in painful positions.
The defense lawyers argue that constituted illegal pretrial punishment and "outrageous government misconduct" that could justify dismissal of the charges, or at least spare the defendants from execution if convicted.
Pohl ordered in 2004 that the Abu Ghraib prison in Iraq be preserved as a "crime scene." He was at the time presiding over the trial of U.S. military police officers accused of torturing and photographing prisoners at Abu Ghraib.
It was unclear whether Pohl had authority to order the preservation of the CIA prisons, if they still exist. The government has kept secret their location, arguing that disclosure could threaten U.S. national security and put allies at risk.
Polish prosecutors are investigating allegations that one of the sites was in Poland, and there is evidence that the CIA set up others in Romania, Lithuania and Thailand, according to reports by the Council of Europe and the United Nations.
The chief prosecutor, Brigadier General Mark Martins, said he does not plan to introduce evidence obtained from the defendants or anyone else via torture, cruelty or inhuman treatment - which is prohibited by U.S. law and international treaty.
In a departure from the Bush administration, the Obama administration has made clear that any interrogation techniques must adhere to those long established in the Army Field Manual, which prohibits torture.
The defendants have been in U.S. custody for a decade, but there are still many legal and evidentiary issues that must be resolved before their trial begins.
Three of them wore camouflage jackets and accessories over their white tunics in court on Monday. As in earlier hearings, they alternated between refusing to answer the judge and critiquing the United States and the court. All five said they understood their legal rights could be compromised if the judge granted their request to skip some court sessions.
"We don't have any motivating factors that would invite us to come to court," said Yemeni defendant Walid bin Attash, who said restrictions at Guantanamo had thwarted efforts to build trust with defense lawyers. (Editing by Tom Brown and Christopher Wilson)