Military prosecutors overseeing the trial of Khalid Shaikh Mohammed, the alleged mastermind behind the September 11, 2001 attacks, have decided not to appeal a recent ruling that excluded a key confession obtained under harsh interrogation methods. The decision marks a significant shift in the government’s long-standing effort to use statements gathered from Mohammed during isolated detentions at secret CIA facilities overseas.

The prosecution team informed victims of the 9/11 attacks and their families of the development on Friday, just days before the 25th anniversary of the terrorist strikes that claimed nearly 3,000 lives in New York, Pennsylvania, and at the Pentagon. Many relatives have expressed frustration at the protracted delays in beginning a scheduled death-penalty trial for Mohammed and three other accused conspirators, which remains set for June 5, 2028, at the U.S. military detention center in Guantánamo Bay, Cuba.

Mohammed’s confession at the center of the dispute was obtained in January 2007 during interrogations conducted by FBI agents at Guantánamo following his years in CIA black sites, where he endured severe treatment, including 183 rounds of waterboarding between 2003 and 2006. The government had maintained that the subsequent statements were given voluntarily and untainted by the earlier harsh conditions.

However, a military judge ruled last month that these confessions were involuntary, citing Mohammed’s restricted access to legal counsel and the failure to inform him that the interrogations could be used as evidence in his prosecution. The prosecution’s liaison to the victims, Danielle Reddan, indicated that appealing the judge's decision could delay the trial or lead to Mohammed being tried separately from his co-defendants, a scenario prosecutors have sought to avoid to minimize the trauma to victims and their families.

The trial initially aimed to try five defendants collectively for their varying roles in the 9/11 conspiracy. However, in 2023, Ramzi bin al-Shibh, accused of being a deputy hijacker, was found mentally unfit to stand trial and was therefore removed from the joint proceedings. The remaining three accused—Walid bin Attash, Mustafa al-Hawsawi, and Ammar al-Baluchi—are currently at different stages of pretrial litigation.

While the confessions of bin Attash and al-Hawsawi are still under review regarding their voluntariness, prosecutors have pursued an appeal aimed at reinstating al-Baluchi’s statements, which were suppressed on grounds of torture and conditions of confinement. These confessions, known as “clean team” confessions, have been described by prosecutors as their strongest evidence.

In the absence of these confessions, the prosecution intends to rely on alternative evidence, including transcripts from covertly recorded prisoner conversations at Guantánamo, financial documents detailing funding linked to the plot, and possibly an interview Mohammed and bin al-Shibh gave to a journalist from Al Jazeera before their capture in Pakistan in 2002.

This is not the first time prosecutors have proceeded without so-called “clean team” confessions in Guantánamo trials. A similar situation unfolded in the case of Abd al-Rahim al-Nashiri, accused of orchestrating the USS Cole bombing, where his FBI interrogations were also suppressed. Prosecutors chose not to appeal in that case, and jury selection for his death-penalty trial is scheduled for October.

Legal analysts note that by foregoing an appeal, prosecutors have not ruled out the possibility of requesting the trial judge, Lt. Col. Michael Schrama, to reconsider his decision. Such a move would require identifying a significant legal error in Schrama’s forthcoming 45-page ruling or relying on changes in legal precedents affecting admissibility of evidence obtained under duress.