Justin Bariso describes 8 ways the FBI spots a liar:

  1. “Come across as empathetic in conversation, and you’ll get the person to open up”
  2. “Ask them something they don’t expect, and they’ll stumble.”
  3. “Liars tend to speak more than truthful people in an attempt to sound legitimate and win over their audience. They will also use more complex sentences to hide the truth.Be wary of the following:
    • Stress usually makes people speak faster.
    • Stressed persons often talk louder.
    • Cracking in the natural tone of voice usually occurs at the point of deception.
    • Repetitive coughing and clearing the throat are signs of tension.”
  4. “A person is often demonstrating deceptive behavior when they:
    • say “no” and look in a different direction;
    • say “no” and close their eyes;
    • say “no” after hesitating;
    • say “noooooooo,” stretched over a long period of time;
    • say “no” in a singsong manner.”
  5. “Be careful if a person:
    • exhibits lapses in memory at critical times (despite being alert in earlier conversation);
    • answers questions with very short answers, refusing to provide details;
    • begins speaking more formally (this is a sign the person is getting stressed);
    • uses extreme superlatives or exaggerated responses (everything is “awesome” or “brilliant” instead of good).”
  6. “ask the person to recall events backward rather than forward in time”
  7. “watch out if someone is trying too hard to make a good impression.”
  8. “If you’re puzzled by a response, explore with follow-up questions.”