To get the truth from someone, you need two sets of skills. The first are the interpersonal skills necessary to get the facts. But the second group of skills is equally if not more they enable you to assess whether the facts actually fit together--whether they are true--and identify the emotions that shaped them.
In Nothing But the Truth , top intelligence experts from the worlds of espionage, business, and law enforcement reveal how they get the information they need and give you the key tools to get the information you need,
A fascinating book by body language and truth detecting expert Maryann Karinch. She outlines many techniques applicable to just about anyone to get the real truth from even the most hard to read people. Highly recommended. A conversation with Maryann Karinch about her book is available here: http://dougmilesmedia.com/?p=1465