I wouldn't throw out all the experts
I've been watching a show on television called "Mind control" and it has a brit (Derren Brown) who is able to tell a great deal about people and whether they are lying simply by observing them and listening to them. Whatever he knows should be taught and learned by interogators. He is absolutely amazing and I believe he is legitimate as he tells you how to do some of what he does as well. Let's use psychology and science to get the best interogators and never torture anyone ever again.
Depends on the rules on fraternization.
That was the short answer; long one is to work at it 24 hours a day and bounce what you learn off at least three different and hopefully unconnected native speakers. Many folks are inclined to have at least a little fun with um, misleading terms, in teaching another their language. I learned more profanity unintentionally than purposely in a couple of languages... :)
Fort Hunt's Quiet Men Break Silence on WWII
From the Washington Post, 6 October 2007:
Quote:
For six decades, they held their silence.
The group of World War II veterans kept a military code and the decorum of their generation, telling virtually no one of their top-secret work interrogating Nazi prisoners of war at Fort Hunt.
When about two dozen veterans got together yesterday for the first time since the 1940s, many of the proud men lamented the chasm between the way they conducted interrogations during the war and the harsh measures used today in questioning terrorism suspects.