Almost two decades after the September 11th attacks, the alleged mastermind behind the deadly plot is once again facing court action before a military tribunal.

A pretrial hearing is underway in Guantanamo Bay for Khalid Sheikh Mohammed and four other defendants. They were arraigned back in 2012, and could face the death penalty if convicted.

For the relatives of 9/11 victims, the development out of Guantanamo brings yet more grief in an already difficult week. Saturday is the 20-year anniversary of the attack.

“It's a new stab in the heart of every family who lost somebody that day,” Bill Tammeus said.

Tammeus’s nephew, Karleton Fyfe, was aboard American Airlines Flight 11, the first to hit the World Trade Center in New York.

“Karleton was a terrific young man. He was 31 at his death,” Tammeus said. “He was married, had a 19-month-old son. His wife had just told him a few days before the plane took off that she was pregnant again.”

In the past decade, the trial has faced numerous delays, including one caused by the COVID-19 pandemic. In addition, there are questions about what evidence can be included at trial after the men faced “enhanced interrogation techniques” while in CIA custody.

The detention of these men and others at Guantanamo has come under international scrutiny, with questions of human rights violations there.

The Biden administration has said they intend to close the facility. Former President Barack Obama failed to shut it down, despite campaign pledges to do so.

After two decades of waiting, Tammeus said justice for his nephew and family would involve getting some answers.

“We would like a full explanation of what happened that day and how it led up to it. We would like to sit in front of those five and have them tell us why they did what they did,” he said.

But with the resolution of any trial still likely a ways off, that wait will continue.