Long-delayed efforts to try self-proclaimed 9/11 mastermind Khalid Sheikh Mohammed and four Al-Qaeda co-defendants finally got under way with a pre-trial hearing at Guantanamo.
Eleven years after the attacks and nine-and-a-half years after his capture in Pakistan, KSM sat on a court bench wearing a white turban, his beard dyed with henna, as victims' family members looked on from behind a glass screen.
KSM is accused of orchestrating the hijacked airliner plot that left 2,976 people dead, while his alleged Al-Qaeda accomplices are charged with providing funding and other support for those who crashed the planes.
All five defendants face the death penalty if convicted, but their trial by military tribunal at the US naval base at Guantanamo, Cuba is not expected to start for at least another year.
"I don't think there's any justice in this court," the 47-year-old Sheikh Mohammed said in Arabic when asked by Judge James Pohl if he understood his rights.
During the five-day pre-trial hearing, the defense is seeking to prevent President Barack Obama's administration from arguing that the treatment and alleged torture of the defendants during interrogations in secret CIA prisons before being sent to Guantanamo in 2006 is classified for national security.
Media organizations and rights groups are demanding that the judge guarantee the transparency of proceedings amid fears that some sessions will be conducted in secret.
"The public has the right to see the proceedings," said James Connell, representing KSM's Pakistani nephew, Ali Abd al-Aziz Ali, who is believed to have helped with logistics and funding for the September 11, 2001 attacks.
The American Civil Liberties Union and media groups petitioning the court are also protesting a 40-second audio delay for journalists and others following the proceedings from behind the soundproof glass.
They say the delay, which allows a military censor to blur statements whose content is deemed a threat to national security, violates speech and press freedoms enshrined in the First Amendment of the US Constitution.
Initially set for June, the pre-trial hearing has been delayed on several occasions for reasons including Ramadan, scheduling conflicts, a train derailment that sparked an Internet outage at the base and a tropical storm.
Pohl turned down a request for a further delay due to rat excrement and mold being discovered in the offices of defense lawyers.
Wearing a hijab out of respect for her Yemeni client Walid bin Attash, defense attorney Cheryl Bormann brought up the issue again Monday, saying the condition of the workspace "makes the staff sick."
Pohl did rule that effective Tuesday, the defendants can leave the courtroom during the hearings or opt not to attend at all.
Michael Schwartz, the military defense attorney for Bin Attash, tried to argue that a discussion of torture was necessary to decide that issue, saying hauling them into court would subject them to emotional strain.
But Pohl shut down his line of reasoning as "irrelevant."
When Pohl tried to make the defendants understand the proceedings would go on without them, even if somehow they managed to escape from the US detention facility, Aziz Ali retorted: "I'll make sure to leave some notes."
KSM, a Kuwaiti-born Pakistani who attended university in the United States, was regarded as one of Al-Qaeda chief Osama bin Laden's most trusted and intelligent lieutenants.
In addition to felling the Twin Towers, the trained engineer claims to have personally beheaded US journalist Daniel Pearl in 2002 with his "blessed right hand" and to have helped in the 1993 World Trade Center bombing that killed six people.
Bin Attash is accused of masterminding the attack on the destroyer USS Cole in Yemen in 2000, which killed 17 US soldiers.
The other co-defendants are Ramzi Binalshibh, a Yemeni who rented a flat in Germany with chief 9/11 attacker Mohammed Atta, and Mustapha al-Hawsawi, a Saudi associate of Bin Laden who is accused of arranging funding for the plot.
Hawsawi's attorney said his client would not attend Tuesday's proceedings.
On Monday, the defendants whispered amongst themselves. At times, KSM read a newspaper, stroking his dyed beard. Hawsawi briefly invoked Allah before giving the name of his new civilian attorney.
The long legal bid to get justice for the 9/11 victims began back in February 2008 when the five men were charged by a military commission set up by former president George W. Bush's administration.
The trial got under way in June 2008 but was scrapped by Obama's administration in 2009 in favor of civilian proceedings in New York in the shadow of where the World Trade Center once stood.
Opposition from Republicans and New York Mayor Michael Bloomberg forced a U-turn in April 2011 as Attorney General Eric Holder announced the five would be tried in Guantanamo by a reformed military tribunal.
They were arraigned on revised charges during a 13-hour hearing in May in which the defendants prayed and refused to speak.