The man who once bragged about planning September 11 "from A to Z" may mount a defence after all to charges that he orchestrated the worst terror attack in US history, with families of the dead watching intently from the US on closed-circuit TV.
Khalid Sheikh Mohammed, charged with four others with planning and helping to carry out the 2001 terror attack that sent hijacked jetliners into the World Trade Centre and Pentagon, will be arraigned today at the US military base in Cuba.
Mohammed had previously mocked the military tribunal and said he would welcome the death penalty.
His co-defendant, Ramzi Binalshibh, also told the court he was proud of the attacks that killed nearly 3,000 people in New York, Washington and Shanksville, Pennsylvania.
But "I don't think anyone is going to plead guilty", said Jim Harrington, Binalshibh's civilian lawyer, who added the defendants are expected to fight the charges against them, which include murder and terrorism and carry a potential death penalty.
Mr Harrington declined to say what would be the basis of his defence and lawyers for Mohammed did not respond to messages seeking comment.
The men, held in a secret prison in Guantanamo that is under such tight security even its exact location on the base is classified, have not been seen in public since a pretrial hearing the day after US president Barack Obama's January 21, 2009, inauguration.
Their arraignment comes more than three years after the Obama administration's failed effort to try the suspects in a federal civilian court and close the prison at the US base in Cuba.
Attorney general Eric Holder announced in 2009 that Mohammed and his co-defendants would be tried blocks from the site of the destroyed trade centre in Manhattan, but the plan was shelved after New York officials cited huge costs to secure the neighbourhood and family opposition to trying the suspects in the US.
Six family members who won a lottery to attend the proceedings will face Mohammed and the other men in court; others were watching on closed-circuit video at military bases in New York City and the eastern US.