The government has secretly destroyed evidence that is relevant to the death penalty trial of the five Guantánamo Bay detainees accused of aiding the terrorist attacks of Sept. 11, 2001, two defense lawyers for Khalid Shaikh Mohammed, the self-described architect of those attacks, said on Wednesday.
The dispute appears likely to add a new chapter to the problems that have plagued the effort to bring the case before a military commission, which has been bogged down for years in pretrial proceedings. The defense lawyers are asking for the judge overseeing the case, Col. James Pohl of the Army, and the prosecution team, led by Brig. Gen. Mark S. Martins, to be recused from further involvement, and for the case to be shut down.
The defense lawyers, David Nevin and Maj. Derek Poteet, said they were not permitted to say what the evidence was, or what exactly had happened to it, because the underlying issue was classified. But Mr. Nevin characterized it as “favorable” to the defendants, and Major Poteet said it was “important or even critical” to an eventual trial, including in terms of weighing what sort of punishment should be imposed if the defendants were convicted.