FORT MEADE, MD. - An architect of the harsh CIA interrogation program created after the Sept. 11 attacks faced men on Tuesday who were subjected to that treatment, appearing as a defense witness in a hearing that could decide whether key evidence against them can be used in their war crimes trial for their alleged roles in the 2001 terrorist plot.



James Mitchell, a retired Air Force psychologist and former CIA contractor, testified for the first time in open court at the U.S. Navy base at Guantanamo Bay, Cuba, where five men face a trial next year by military commission for their alleged roles planning and aiding the Sept 11 attacks.



Mitchell agreed to come to Guantanamo to testify without a subpoena to give his version of events, which he also detailed in a book called ``Enhanced Interrogation,`` that he co-wrote with a CIA spokesman.



“I'm happy to talk about my role in the program and what the program did,” he told the court.



At times, however, he appeared to bristle at the questioning. When defense lawyer James Connell thanked him for coming to court, he replied,”`I did it for the victims and families not for you.”



Mitchell and another psychologist, Bruce Jessen, were contracted by the CIA to develop the interrogation program, which included waterboarding, intense sleep deprivation and prolonged shackling in “stress positions” and is now widely regarded as torture.



Defense lawyers for the five men charged in the attacks have called the contractors, who observed and took part in interrogations at clandestine CIA facilities, as witnesses in an effort to disqualify statements the defendants made to the FBI.



Mitchell and Jessen gave depositions in a lawsuit filed by the American Civil Liberties Union on behalf of three former prisoners, including one who died in custody. The case was settled for undisclosed terms in August 2017 and the two former contractors did not testify in court.



Their testimony in Guatnanamo is an important milestone in the Sept. 11 war crimes proceedings, which have been bogged down in the pretrial phase since the men were arraigned in May 2012.



“This testimony marks a critical moment for reckoning with the torture committed in the American people's name,`` said ACLU staff attorney Dror Ladin, ``Mitchell and Jessen, along with collaborators in the U.S. government, are responsible for shameful cruelty that the CIA is still trying to cover up.”



Mitchell was expected to be followed on the stand by Jessen. Their testimony will likely take up much of a pretrial hearing scheduled to last two weeks.



The defendants include Khalid Shaikh Mohammad, an al-Qaida operative who has portrayed himself as the mastermind of the Sept. 11, 2001, attacks. All five face the death penalty if convicted of charges that include terrorism and nearly 3,000 counts of murder for their alleged roles planning and providing logistical support to the hijacking plot.



Under a 2006 law that set up the military commission, any statements must be voluntary to be admitted into evidence and the government is not seeking to use at the trial anything the men said while in CIA custody.



But the prisoners also gave what prosecutors have called ``clean'' statements to the FBI after they arrived at Guantanamo and were placed in military custody in September 2006 after several years at CIA facilities.



Lawyers for the five defendants argue that everything the men have said in custody was tainted by the torture they were subjected to while in CIA confinement.



James Connell, a lawyer for defendant Ammar al-Baluchi, said he believes the FBI helped guide some of the questioning of the men while they were in CIA custody.



“Our global goal is to have all the statements thrown out,'”Connell said before the hearing.



A Senate investigation in 2014 found that the interrogation program designed by Mitchell and Jessen was used on 39 detainees and produced no useful intelligence. They were paid $81 million for their work, according to the Senate report.



Mitchell and Jessen previously worked at the Air Force survival school at Fairchild Air Force Base outside Spokane, Washington, where they trained pilots to avoid capture and resist interrogation and torture. The CIA hired them to reverse-engineer that training to break terrorism suspects.



They defended their work when the lawsuit was settled, arguing that neither contractor condoned or conducted any mistreatment of prisoners and that the overall program was authorized by the government.



Jessen said in a statement then that he and Mitchell ``served our country at a time when freedom and safety hung in the balance.''



The proceedings at Guantanamo were being transmitted to several government installations in the U.S., including Fort Meade, Maryland, where they were viewed by The Associated Press.