You are correct that relationship- (or confidence-) building approaches are not new and have been known to law enforcement for decades. Even World War II interrogators used relationship-building approaches to great success, but we can build on that. Interrogation is an art and a science and, like every discipline, can be improved upon. My group began to integrate relationship-building with other criminal investigative techniques, always tailoring it to the culture at hand. This is what made our techniques new. I watched day in and day out as my group of interrogators used American ingenuity in adapting these approaches for each individual detainee and they were highly effective. Interrogation is about being smarter, not harsher.
Why these techniques have not yet been integrated into intelligence interrogation is a mystery to me. I made a list of criminal investigation techniques that would be effective in interrogations and included it in my “after-action” report. The next administration needs to institutionalize this approach by contracting a cadre of experienced law enforcement officers to help train our intelligence interrogators. This same relationship already exists between civilian and military criminal investigators.
See also: Matthew Alexander’s WaPo editorial