How do you know if someone is lying to you? Sure, some lies are obvious, but most are not. And some lies matter to you and others don't. But when you are discussing a critical matter, knowing whether you are being told the truth or not can make a huge impact on the outcome. The fact is that there is no fool-proof method for doing this, but there are techniques that can help.
One place to go for answers would be to those who need to determine the level of truth in people's statements for a living. Places like the CIA. More on page two.