Even if you think you already know something about body language, facial emotional reflectors are much more involuntary and unconscious reactions.
It is hard to conceal what you are actually feeling. These traces of evidence of truth will appear as a brief, involuntary facial expression revealing how one really feels and thinks behind those spoken words or actions; or what one is trying hard to conceal.
You will be taught how to set up the right questioning environment that will expose maximum emotional reflectors of your subject. This has proven very effective even against the most trained individual. Former President Clinton was caught lying about his affair with Monica Lewinsky using these techniques.