Three men accused of being involved in the 9/11 terrorist attack – including the self-proclaimed mastermind of the 2001 attacks on the World Trade Center and the Pentagon – have agreed to plea deals at Guantánamo Bay, Cuba, prosecutors said on Wednesday. “The Convening Authority for Military Commissions, Susan Escallier, has entered into pre-trial agreements with Khalid Sheikh Mohammed, Walid Muhammad Salih Mubarak Bin ‘Attash, and Mustafa Ahmed Adam al-Hawsawi, three of the co-accused in the 9/11 case,” the Pentagon said in a short statement. The New York Times reported that the three will plead guilty to conspiracy charges in exchange for a life sentence rather than a death-penalty trial. The men have been in US custody since 2003 and Khalid Sheikh Mohammed is widely seen as the chief plotter of the terror attacks. Over the years, the case had become bogged down in lengthy pre-trial proceedings. Defense lawyers had argued that the men’s torture in secret CIA prisons had rendered the evidence against them unusable in legal proceedings. The deal avoids both the prospect of a hugely lengthy and complex trial, or the possibility that confessions seen as crucial to the case would be thrown out. The New York Times reported that news of the deal emerged in a letter from prosecutors to family members of victims of the devastating attacks that killed almost 3,000 people. “In exchange for the removal of the death penalty as a possible punishment, these three accused have agreed to plead guilty to all of the charged offenses, including the murder of the 2,976 people listed in the charge sheet,” said the letter, according to the newspaper. Prosecutors said that Mohammed, who was an engineer and educated in the US, brought the idea of flying planes into buildings to the al-Qaida leader Osama bin Laden and then helped train and direct some of the hijackers who carried out the devastating attacks on US soil. Mohammed and Hawsawi were captured together in Pakistan in March 2003. The pair were tortured by their US interrogators, including subjecting Mohammed to a record 183 rounds of waterboarding.