I wouldn't be in it for the information. By then I will already have positively identified the culprit. Perhaps my methods would, instead, be for some other insidious purpose...
Ironically it was a Luftwaffe Commandant who adopted the friendly questioning method as far more effective which sorta became a guidebook for the CIA.
https://en.m.wikipedia.org/wiki/Hanns_ScharffHanns Scharff, a German WWII pilot interrogator, is considered the most successful interrogator of all time. In fact, he was so successful, he helped in shaping the U.S. interrogation techniques after the war. But how did he do it?
According to his own words, Scharff developed several techniques that helped him in his interrogations. First of all, instead of torturing or degrading prisoners, Scharff offered them courtesy and what appeared to be consideration. Instead of attempting to coerce or persuade with offers of booze and prostitutes, Scharff and his fellow officers took prisoners to whatever cinema shows were available at camp, and even shared tea and coffee with them, when they could get it.
According to Scharff, Prisoner of War (POW) interrogations should consist of three phases. First is to help the POW relax and feel comfortable by making small talk about anything at all. Second, after he’s loosened up, the questioner should try to get the prisoner to reveal any military information or plans that he might know, ideally without letting him realize he has said anything of value. Third, the interrogator must write an evaluation report that is truthful, and that contains any and all information that might be useful to commanding officers in the field.
"So why did you sell a Shelby part you never owned? More tea?"