9/11 anniversary: Four alleged plotters are still awaiting trial 25 years after the attack that killed 3000; even their 2028 trial date is uncertain

Today marks the 25th anniversary of the Sept. 11, 2001, terrorist attacks that killed nearly 3,000 people. Yet, a quarter-century later, four alleged plotters of the attack, including its accused mastermind Khalid Sheikh Mohammed, are still awaiting trial.

Last month, a U.S. military judge set a summer 2028 trial date for Khalid Sheikh Mohammed and three other men accused of plotting the Sept. 11 attacks. The trial is scheduled to begin June 5, 2028 — 18 months later than the January 2027 start that prosecutors had requested. The additional time is needed to resolve pretrial disputes, including disagreements over what evidence can be presented at trial, Air Force Lt. Col. Michael A. Schrama wrote in his ruling.

The U.S. military and successive administrations have struggled for more than two decades to bring to trial the man accused of planning one of the deadliest attacks on U.S. soil. Even the 2028 date is not guaranteed, as the case still has to clear numerous pretrial deadlines and legal disputes. A trial had previously been scheduled for 2021 but was later canceled.

Who are the alleged plotters?

The four defendants set to stand trial together are Khalid Sheikh Mohammed, Walid bin Attash, Ammar al-Baluchi, also known as Ali Abdul Aziz Ali, and Mustafa al-Hawsawi. They face charges including conspiracy, murder in violation of the law of war, terrorism and hijacking. Prosecutors are seeking the death penalty.

Mohammed, commonly known as KSM, is accused of developing and directing the plot to hijack commercial aircraft and use them as weapons against the World Trade Center and the Pentagon. A fourth hijacked plane crashed into a field in Pennsylvania after passengers attempted to regain control. The three other defendants are accused of helping Mohammed execute the plot. They are among the last detainees still held at the U.S. military base at Guantánamo Bay, Cuba.

Mohammed was captured in Pakistan in 2003 and held in secret CIA custody for years before being transferred to Guantánamo in 2006. His own statements have become important pieces of the government's case — but they have also become one of the biggest obstacles to bringing the case to trial.

Why has the 9/11 trial been delayed for so long?

The extraordinary delay stems from a combination of legal, procedural and logistical complications created by the decision to prosecute the defendants through a military-commission system rather than ordinary federal courts. Experts told CBS News that the U.S. made the case significantly more complicated by choosing this route. Instead of treating the alleged al Qaeda operatives as traditional criminal defendants, the Bush administration developed military commissions at Guantánamo to prosecute terrorism suspects for alleged war crimes.

The system was subsequently altered by Congress and the Supreme Court, creating years of disputes over procedures and defendants' rights.

Notably, the trial saw several judges over the years; Air Force Lt. Col. Michael Schrama is the fifth judge to oversee the case since the defendants were arraigned in 2012.

CIA, FBI interrogations created hurdles

As per reports, Mohammed's years in secret CIA custody have generated perhaps the most consequential legal battle in the case. He was allegedly subjected to coercive interrogation techniques, including waterboarding. His lawyrs have argued that statements he later made to U.S. investigators were tainted by that treatment and therefore should not be admitted as evidence. That has led to years of litigation over interrogation records, classified information, the circumstances of the defendants' detention and whether later statements were voluntary.

In August, Schrama ruled that prosecutors had not established that statements Mohammed made to the FBI in 2007 were voluntary and excluded them from evidence. The ruling does not necessarily end the government's case. Prosecutors have other evidence, including documentary and communications records. But losing the statements could make it more difficult to connect the evidence and prove the government's case. Prosecutors also chose not to appeal the ruling, partly because another appellate fight could put the June 2028 trial date at risk.

Guantánamo makes even routine hearings difficult

The location of the trial has added another layer of complexity. Unlike a federal courthouse in the U.S., where lawyers and judges can appear for hearings on a regular basis, Guantánamo requires much of the legal system to travel to the military base in Cuba.

For a hearing, judges, prosecutors, defense lawyers, witnesses, court staff and sometimes victims' family members must travel from the U.S. to Guantánamo. The system has also seen personnel rotate in and out, forcing lawyers to revisit even relatively basic procedural questions. All of this has contributed to a case that has remained stuck in pretrial proceedings for years.

The plea deal that fell apart

The case took another major turn in 2024, when Mohammed and two co-defendants reached plea agreements that would have spared them the possibility of execution in exchange for guilty pleas and life sentences without parole.

The agreements also would have required the men to answer lingering questions from victims' families about the attacks. After two years of negotiations, however, the plea agreements were repudiated by the Biden administration and ultimately abandoned, sending the case back toward a trial. A federal appeals court later threw out an agreement that would have allowed Mohammed to plead guilty while avoiding the death penalty.

Will there finally be a trial in 2028?

For now, June 5, 2028 is the date set for jury selection and the beginning of the trial. But even that date is not certain. The defense and prosecution still have numerous pretrial disputes to resolve, and the case has repeatedly demonstrated how easily new legal battles can push the proceedings further into the future.

For many victims' families, the delay has become part of the tragedy itself: some relatives who wanted to see the accused men convicted or acquitted have died before the case ever reached a courtroom. The question now is not simply whether the U.S. can secure a conviction. It is whether, 25 years after the attacks, the case can finally make it through the complex military-commission system and reach a verdict.