I read recently that the easiest way to tell if someone is lying is to ask them to send you their statement in an email. They had surveyed and found people were least willing to lie in such a format. Any other good ways?
“I like your haricut”.
“Can you email that to me?”
“Huh?”
“Lying bitch!”
mmm
If the lie can get them sued, I can see someone hesitate to put it in writing, but generally people who will lie to your face will lie in an email.
What sort of lies are you trying to deduce?
Are they a lawyer, teenager or politician whose mouth is moving?
Just kidding: I’m not sure exactly what you’re asking. Can you expound?
Just ask them to elaborate. Most lies depend on the person lied to not asking too many further questions.
For many people, you can see if their mouth is open.
Business liars, salesman liars, or social liars?
First ask them if they are a policeman. The police are not allowed to lie to you.
At least that’s what I’ve read on the dope. 
How reliable is body language detectors?
I guess microexpression are even more accurate…