Special Agent Technique: How To Tell If Someone Is Lying

As an agent you are lied to on a daily basis. Additionally, as an undercover agent I often had to lie. Because of this I had to learn how to determine if someone was lying to me and also how to mask my lie while undercover.

I remember once I had this military member who was turned in for breaking into local public schools and stealing whatever he could. I was a rather new agent and I brought the guy in and interrogated him for about an hour before going to a senior agent working the case with me and telling him, “look, this guy is innocent. We should cut him loose.”

The senior agent had been watching from the observation room and he said, “Derek, give me a minute.”

He went into the room for about 5 minutes, came out and then said, “all right, you can go in and take his confession now.”

I was shocked and embarrassed. This guy had lied to me for over an hour and I had no clue. My more experienced partner recognized the clues he saw and heard from the observation room and broke this guy in minutes.

Knowing how to recognize these clues is a great skill to have, both for an agent, and for you when dealing with people on a daily basis.

Detecting liars is often part of the job for special agents and we often look to facial expressions, body language, and verbal indicators as signals, or “tells,” that someone is lying to us.

There are a number of facial expressions and associated reactions that could indicate someone is lying to you. This is often caused by nervousness, or by chemical reactions or physical reactions that the person will have a hard time hiding from you.

To start, it would be good to know how the person you are talking to normally acts. But sometimes in conversation you are just meeting the person and know their actions, so you have to do the best you can.

It’s best to observe someone for a while as you make small talk or ask innocuous questions, in order to see what his usual reactions are. Then if he exhibits several lying indicators when you ask more pointed or suggestive questions you can be confident that he’s likely lying to you.

Here are some of the facial expressions and actions I suggest you look out for:

1. Eyes moving back and forth

Sometimes I would interview a “perp” and he would move his eyes back and forth when I was talking to him.

This is a physiological reaction to him feeling uncomfortable or trapped by my questions when he does not what want to answer them.

This stems from when people had to seek an escape route when they feared they were in a dangerous situation, such as facing a human or animal adversary.

It is a dead giveaway for lying. Just like the dangerous situation, he is trying to get out.

2. Rapid blinking

Usually a person blinks about five or six times a minute. However, when a person is stressed from lying, he might blink five or six times very rapidly.

In relation to this, when a person closes his eyes for a second or two after telling you a lie, this may indicate he’s just lied to you, since this is a type of defense mechanism.

3. Looking up to the right

Here is one of my favorite giveaways that I often look for. If I am interviewing a right handed witness and I ask about something he’s supposed to have seen, if he looks upward and to his left, he’s truly accessing his memory of the incident.
However, if he looks upward and to his right, he’s accessing his imagination, and he’s inventing an answer.

You see the left side of your brain is the side where we recall information and the right side is the creative side. Left-handed people will usually have just the opposite reactions.

4. Looking directly to the right

If I ask a person what he has heard, his eyes will shift toward his left ear to recollect the sound he heard, but if his eyes shift toward his right, he’s about to tell you a lie.

5. Looking down to the right

If a person is going to tell you his memory of a smell or touch or sensation, his eyes will shift downward and to his left. However, if his eyes shift down and to his right, he’s lying

6. Touching his face

Believe it or not, there is a chemical reaction that causes people’s faces to itch when they lie. Look for this!

7. Pursed lips

If a guy is telling you a lie, his mouth will often become very dry. In order to overcome this, he might do a sucking motion, pursing his lips, so this is another indication of lying.

If his lips are so tightened that they appear pinched and white, then he is probably lying.

8. Excessive sweating

If you are talking to a person and sweat appears on his forehead, cheeks, or back of the neck, he might be lying (of course it could just be hot outside or in the room.)

He will probably try to wipe it away. This is just another indicator that you can watch for along with everything else.

9. Blushing

Blushing is another indicator of a person lying to you.

It is an involuntary reflex caused by sympathetic nervous system (this activates your fight-or-flight response) and is a response to the release of adrenaline, which may be released if he is lying.

10. Head shaking

If I am interviewing or talking to a person and he is telling me the truth, he will nod his head simultaneously in agreement with what he is saying. However, if he starts shaking his head in disagreement with what he said, his body is giving away his lie

So I have given you 10 things to look for to tell if a person is lying. Of course it is not 100% perfect, but it is what we learned as agents and it gives you a good indication, especially when the person is doing more than one of these things.

Practice these techniques so you can recognize them easily, but don’t give away your secrets because the person will try to hide his actions if he knows what you are doing.

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About Derek Smith

Derek is a former Federal Special agent and Veteran of 3 military services. He knows a great deal about self-defense and he shares his knowledge with you!


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