"Enhanced interrogation" methods don't work, but according to the US government's High Value Detainee Interrogation Group, the following strategies, outlined in Scientific American, can be quite effective:
Fill in the blank. To get that info, instead of asking direct questions, tell your target a story about what he or she did, leading the person to believe you already know what happened. As you provide the narrative, the guilty party will then supply details and corrections. This is called the Scharff technique, named for its developer, Hanns Scharff, a German interrogator during World War II. The technique was shown to elicit more information than direct questioning in a 2014 study. People interrogated using this method also tend to underestimate how much they are sharing.Ask for the story backward. In contrast to what most people believe, truth tellers are more likely to add details and revise their stories over time, whereas liars tend to keep their stories the same. "Inconsistency is really just a fundamental aspect of the way memory works," Meissner says. A technique that interrogators use to capitalize on that quirk is called reverse telling—asking people to recall events backward rather than forward in time. This strategy has a double effect: For truth tellers, it makes recall easier—in another HIG study, reverse telling produced twice as many details as did recounting chronologically. For liars, the task becomes harder when put in reverse; they become more likely to simplify the story or contradict themselves.
Other strategies are summarized in this Scientific American article.
The science is laid out in this special issue of the journal of Applied Cognitive Psychology: Information gathering in law enforcement and intelligence settings: Advancing theory and practice
