Here's the scoop from Greg Hartley, interrogation expert and author of How to Spot a Liar. First, know this: liars stress out trying to keep their story straight. Which means they often do things that can tip you off. So, ask them something they'd have no reason to lie about, like "Where's the nearest Starbucks?" Once you've seen their normal speech patterns and eye movements - ask what you really want to know, and watch for these clues that they may be lying:

• Their voice becomes higher pitched because stress causes extra tension in their vocal cords.
• Liars also pause a split-second longer than usual before they answer a question.
• And they "self-comfort" more often   like, stroking their beard, or fidgeting with jewelry.
• The fourth way to tell someone's lying: they blink less often, and their pupils get larger.
• Also, a liar's body movements become jerky, and they switch positions or change topics fast.
• And the final "tell" that someone's lying: they use fewer first-person pronouns, like "I" or "me".

Instead they shift attention   and blame   elsewhere by saying "It was" or "They wanted to." If you'd like to go further, the book is: How to Spot a Liar by Greg Hartley.