FILE - This Monday, Dec. 8, 2008 courtroom drawing by artist Janet Hamlin and reviewed by the U.S. military, shows Khalid Sheikh Mohammed, center, and co-defendant Walid Bin Attash, left, attending a pre-trial session at Guantanamo Bay Naval Base, Cuba. (AP Photo/Janet Hamlin, Pool, File)

WASHINGTON (AP) — Lawyers for accused 9/11 mastermind Khalid Sheikh Mohammed are urging a federal appeals panel to let his scheduled guilty plea Friday n Guantanamo Bay, Cuba, go forward in a plea agreement that would spare him and two co-defendants the risk of the death penalty in al-Qaida’s notorious Sept. 11, 2001, attacks.

Defense lawyers in a filing late Wednesday described Defense Secretary Lloyd Austin’s attempts to throw out a plea deal that his own military had negotiated and approved as the latest in two decades of “fitful” and “negligent” mishandling of the case by the U.S. military and successive administrations.

Mohammed is due to enter his plea Friday morning in the attacks, in which 19 al-Qaida hijackers smashed airliners into the World Trade Center and the Pentagon and another crashed into a Pennsylvania field, killing nearly 3,000 people. Family members of some of the victims are gathered at Guantanamo for the moment.

Austin unexpectedly renounced the plea agreement after it was announced this summer, and the Biden administration’s Justice Department is seeking to block Mohammed’s plea from going forward at a U.S. military commission courtroom.

“An 11th-hour stay will accomplish nothing but more delay and it will reward the government for its — at best — negligent handling” of the 9/11 prosecutions, Mohammed’s lawyers argued in a filing to a District of Columbia federal appeals panel just before midnight.

The federal appeals panel appears on track to possibly rule Thursday on the request by the Democratic Biden administration.

Legal and logistical challenges have bogged down the 9/11 case in the 17 years since Mohammed, who prosecutors say conceived the idea of using hijacked planes in the attacks, was first charged. The case remains in pre-trial hearings, with no trial date set.

Years of defense and prosecution testimony are ongoing about how much the sustained torture of Mohammed and other defendants in CIA custody renders their later statements legally inadmissible.

With the prosecution in the Sept. 11 attacks dragging on for decades and no conclusion in sight, military prosecutors this summer notified families of the victims that the senior Pentagon official overseeing Guantanamo had approved a plea deal after more than two years of negotiations.

The deal was “the best path to finality and justice,” military prosecutors told families then. In it, Mohammed and co-defendants Walid bin Attash and Mustafa al-Hawsawi agreed to plead guilty to 2,976 murder charges in exchange for life sentences.

Austin unexpectedly announced Aug. 2 that he was nullifying the plea deal, and he has fought since then to scrap it. He argues that a decision on death penalties in an attack as grave as Sept. 11 should only be made by the defense secretary.

Defense attorneys say that the plea agreement is already in effect and that Austin has no legal standing to throw it out after the fact. The Biden administration went to the federal appeals court Tuesday after the Guantanamo judge and a military review panel sided against Austin’s request.

Mohammed’s attorneys argued in the new filing that Austin’s “extraordinary intervention in this case is solely a product of his lack of oversight over his own duly appointed delegate,” meaning the senior Pentagon official overseeing Guantanamo.

The Justice Department’s brief earlier this week said that the government would be irreparably harmed if the guilty pleas were accepted for Mohammed and the two co-defendants in the Sept. 11 attacks.

It said the government would be denied a chance for a public trial and the opportunity to “seek capital punishment against three men charged with a heinous act of mass murder that caused the death of thousands of people and shocked the nation and the world.”