The men accused of planning the 9/11 terrorist attacks are expected to plead guilty, according to the Department of Defense.

Khalid Sheikh Mohammed and two accomplices are expected to enter the pleas at a military commission at Guantanamo Bay, Cuba.

Sept. 11 first responder and advocate John Feal says the pleas could bring some relief to the families who lost loved ones from the attacks.

"We already knew they were guilty, they just did that so they don't get the death penalty,” said Feal. "If it brings the families closure and if it brings them peace and calm, I support that.”

Joe Gildea is a former FDNY firefighter who lost 14 members of his firehouse on 9/11.

"I'm glad that our government is still pursuing justice,” he said. "It's a good day, it's not a great day. I still think he deserves the death penalty."

The plea agreements come nearly 16 years after their prosecution began, but advocates and first responders say justice is far from over.

"You can never forget,” said Gildea. “I think it's the most critical thing to just hunt everybody down and the families need answers."

Pentagon officials declined to immediately release the full terms of the plea bargains, but according to letters sent to victims' families, defense lawyers have requested the men receive life sentences.

Mohammed and the two accomplices are expected to enter their guilty pleas as early as next week.