Khalid Sheikh Mohammed, the suspected architect of the Sept. 11, 2001, attacks and his fellow defendants may never face the death penalty under plea agreements now under consideration to bring an end to their more than decade-long prosecution, the Pentagon and FBI have advised families of some of the thousands killed.

The notice, made in a letter that was sent to several of the families, comes 1.5 years after military prosecutors and defense lawyers began exploring a negotiated resolution to the case.

The prosecution of Mohammed and four others held at the U.S. detention center in Guantanamo Bay, Cuba, has been troubled by repeated delays and legal disputes, especially over the legal ramifications of the interrogation under torture that the men initially underwent while in CIA custody. No trial date has been set.

“The Office of the Chief Prosecutor has been negotiating and is considering entering into pre-trial agreements,” or PTAs, the letter said. It told the families that while no plea agreement “has been finalized, and may never be finalized, it is possible that a PTA in this case would remove the possibility of the death penalty.”

Some relatives of the nearly 3,000 people killed outright in the terror attacks expressed outrage over the prospect of ending the case short of a verdict. The military prosecutors pledged to take their views into consideration and present them to the military authorities who would make the final decision on accepting any plea agreement.

Jim Riches, who lost his firefighter son Jimmy in 9/11, went to Guantanamo for pretrial hearings in 2009. He remains deeply frustrated that the case remains unresolved 14 years later. He said he laughed bitterly when he opened the government’s letter Monday.

“How can you have any faith in it?” Riches asked. The update “gives us a little hope,” he said, but justice still seems far off.

“No matter how many letters they send, until I see it, I won’t believe it,” said Riches, a retired deputy fire chief in New York City. He said he initially was open to the use of military tribunals but now feels that the process is failing and that the 9/11 defendants should be tried in civilian court.

The Obama administration at one point sought to do so, but the idea was shelved because of opposition from some victims’ relatives and members of Congress and city officials’ concerns about security costs. As the 22nd anniversary of the attacks approaches, “those guys are still alive. Our children are dead,” Riches said.