How do you find out if someone is telling you the truth?

Well, there are many ways that I could go about finding out whether or not someone is telling the truth.  I would start off by asking the person questions that would give me some clues. I would the same question, but I would rephrase the question so that it would force the person to answer a different way.  

A good way to find out if someone is telling you the truth is by their body language.  Body language can say a lot about how a person is feeling.  Usually if someone is telling the truth, their body positioning would be more laid back and open because they have nothing to hide.  Also, most people do not have a problem making eye contact with the person they are talking to.  Someone who is telling the truth probably would not have a difficult time trying to sit still without fidgeting. 

Emotional gestures is also a way of telling whether or not someone is telling the truth.  For example: we know when someone is putting on a fake smile. Also, someone who is telling the truth does not get all defensive when they are talking.  An innocent person has no problem facing the person they are talking to.

Something that I pay close attention to is when the subject is changed and the person who is lying then becomes more relaxed because they are no longer being interrogated.  The person who is telling the truth may want to continue talking about the situation because they want the person to believe that they are telling the truth.

That is how I would determine whether or not I think someone is telling the truth.