This article was produced in partnership with the Pulitzer Center on Crisis Reporting.
GUANTÁNAMO BAY, Cuba — An architect of the C.I.A.’s Bush-era interrogation program, who personally waterboarded the man accused of masterminding the Sept. 11 attacks, testified for the first time to the war court at Guantánamo Bay on Tuesday, defiantly facing defendants who had been subject to his methods.
James E. Mitchell, a former contract psychologist for the intelligence agency who helped develop what the government euphemistically called “enhanced interrogation techniques,” appeared in court as a witness, confronting five men who had been subject to elements of his program of violence, sleep deprivation and humiliation. Among them was Khalid Shaikh Mohammed, who is charged with leading the planning for the Sept. 11 attacks and was waterboarded 183 times by a team including Dr. Mitchell.
Dr. Mitchell opened what is expected to be two weeks of testimony by telling defense lawyers that the only reason he had come to Guantánamo was to testify in person in front of families of the 9/11 victims. He was appearing at a pretrial hearing for the five men facing charges in the 9/11 case. They are seeking to have the court throw out as evidence statements they made to the F.B.I. after coming to Guantánamo, saying that their interrogations in C.I.A. custody had conditioned them to tell their captors what they wanted to hear.
“You folks have been saying untrue and malicious things about me and Dr. Jessen for years,” Dr. Mitchell said, referring to John Bruce Jessen, another psychologist who worked with him to design what amounted to a torture program for the C.I.A. to use on its captives held in secret prisons after the 2001 attacks and the subsequent invasion of Afghanistan.
Had Dr. Mitchell refused to come, the Air Force colonel presiding in the case could have ordered him to testify by video teleconference from Washington.
“I actually did it for the victims and families. Not you,” Dr. Mitchell said under questioning by James G. Connell III, a lawyer for one of the defendants. About 12 relatives of 9/11 victims and their companions were observing the hearing, one wearing a necktie with the Statue of Liberty on it.
They were sequestered behind a blue curtain in the court’s spectator’s gallery, hidden from view of the troops, journalists, legal observers and court staff also watching what is expected to be the most dramatic testimony so far since arraignment of the five men in the case in May 2012.
Dr. Mitchell entered the courtroom just before 11 a.m., and took the witness stand 25 feet away from Mr. Mohammed, who put on a pair of eyeglasses and looked across the room but displayed no evident emotion. Mr. Mohammed said something inaudible to a co-defendant, Walid bin Attash.
For the testimony, two defense teams had mental health professionals in the courtroom. Beside Mr. Mohammed was Dr. Katherine A. Porterfield, a New York psychologist. Dr. Stephen N. Xenakis, a retired Army general and psychiatrist, sat beside another defendant, Mr. Mohammed’s nephew, Ammar al Baluchi.
Dr. Mitchell, with a full snow-white beard and thinning white hair, wore a charcoal suit to court with a crisp white button-down shirt and a red tie. Mr. Mohammed was in his typical court attire — a green camouflage hunting jacket atop white flowing clothes, a black and silver stripped scarf fashioned into a turban and black orthopedic shoes.
Dr. Mitchell adopted an aggressive approach as a witness. After a prosecutor provided him with a Top Secret guide to the codes the United States government had assigned to interrogators whose names cannot be used in court, he declared the list flawed. He said it gave a “false and misleading impression that these men were interrogated during their entire time in custody. And they were not.”
He said some of the code-named people identified as interrogators were actually “debriefers, targeters and analysts.”
In 2002, Dr. Mitchell and Dr. Jessen devised the interrogation program that the C.I.A. would employ on detainees. Defense lawyers say all five men charged with conspiracy in the 9/11 attacks were tortured using some of those now-outlawed measures. The defendants all face the death penalty. Their trial is scheduled to get underway next January.
Drs. Mitchell and Jessen were called by lawyers to testify for Mr. al-Baluchi. But all five defense teams are expected to question them about what went on in the clandestine overseas prisons, including one in Thailand that for a time was run by Gina Haspel, now the C.I.A. director.
Mr. al-Baluchi’s lawyer, Mr. Connell, is spearheading the effort to persuade the judge to exclude from the trial the testimony of F.B.I. agents who questioned the defendants at Guantánamo in 2007. It was just months after their transfer there from years in C.I.A. prisons, and the defense lawyers argue that, although there was no overt violence during the F.B.I. interrogations, the defendants were so thoroughly broken by their interrogations in the black sites that they were powerless to do anything but tell the F.B.I. agents what they wanted to hear.
By law, prosecutors can use voluntary confessions only at the military commissions at Guantánamo.
Dr. Mitchell has described waterboarding and other violence as well as sleep deprivation and forced nudity as part of a program of “conditioning” captives to cooperate that has no long-lasting effect on them.