WASHINGTON  Jim Mitchell and Bruce Jessen were military retirees and psychologists, on the lookout for business opportunities. They found an excellent customer in the Central Intelligence Agency, where in 2002 they became the architects of the most important interrogation program in the history of American counterterrorism.

They had never carried out a real interrogation, only mock sessions in the military training they had overseen. They had no relevant scholarship; their Ph.D. dissertations were on high blood pressure and family therapy. They had no language skills and no expertise on Al Qaeda.

But they had psychology credentials and an intimate knowledge of a brutal treatment regimen used decades ago by Chinese Communists. For an administration eager to get tough on those who had killed 3,000 Americans, that was enough.

So “Doc Mitchell” and “Doc Jessen,” as they had been known in the Air Force, helped lead the United States into a wrenching conflict over torture, terror and values that seven years later has not run its course.