What are signs that someone is a fool

How liars tell the truth

4 Sep 2019 - DuchRuudje van Gerwen

Nico Declercq is a criminal investigator with experience interviewing people. For him, as an expert in body language and lie detection, the ultimate goal of the investigation is not to uncover lies, but to find out the truth.

As a criminal investigator, I conduct investigations that often involve extreme and emotional events. For example, it is about a fire that burned down a house, a bad work accident or loss of millions. In all of these cases, I go to the scene and talk to the people involved. I don't do that over the phone or by email. I have to face people when I ask them questions. As Nietzsche already established in the 19th century, people lie with their mouths, but their facial expressions speak the truth. There are three different types of clues that will help me distinguish a true story from a lie:

  • Nonverbal cues
  • Paraverbal cues
  • Verbal cues

Non-verbal cues are about body language and facial expressions. The way people talk is called paraverbal communication. The verbal clues are hidden in the words, in the actual story that people tell me. My job as an investigator is to watch and listen carefully to find out the truth.

How our body betrays us

A liar can make up a story and try to fool me with verbal language. But body language follows its own rules. There are some tell-tale signs that a person may be lying - or telling the truth. It doesn't work the way it often does in television series Lie to me is shown where an expert is watching the video of a survey and says: "Stop, stop, he's lying."

My approach to a survey involves the following steps: matching, observing, researching. During the comparison phase, I ask the interviewed a few questions whose answer I already know, for example about their name. In this way I get to know their normal facial expressions and body language as well as their normal language pattern. There are some non-verbal criteria such as micromimic (fleeting facial expressions that last only a fraction of a second), changes in eye contact, and eye movements.

For example, if you ask someone how many doors there are in their house, you will often see that the person is looking up to the right. She doesn't do this because she expects the answer to magically appear on the ceiling, but because memory is on the right side of the brain. That doesn't mean you can go home and ask your wife or husband, "Have you ever cheated on me?" And then realize that he / she is lying, depending on which way he / she is looking. This is just a small indication that there may be some deception here. I pay attention to non-verbal criteria, and when I see something that suggests the person may be lying, I start asking a lot of questions.

How our language betrays us

In addition to non-verbal communication, it's important to watch out for paraverbal cues that people inadvertently reveal when making up a story. Liars give much shorter answers and don't reveal details. They also take longer pauses between words and sentences. Sometimes liars try to fill in these pauses by, for example, repeating the question they were asked. Another indication that someone is just making up a story is that he or she is suddenly stammering a lot more. All of these clues stem from the fact that liars have a very simple version of a story up their sleeve when compared to a person telling the truth.

How our words betray us

The difference between someone telling the truth and someone telling a lie is similar to the difference between a tree and a broomstick. A tree is a complex organism with branches, leaves, flowers and fruits growing on it. This level of complexity also characterizes a true story: it is full of emotions, interactions, sensory observations, unexpected events. Just like a tree, a true story is made up of many details, while a broomstick is just a straight piece of wood. It's not a complete story.

For example, tonight, if your husband or wife says, “I went out for a drink with someone,” you may want to start asking questions. A lack of detail could mean there is only a broomstick, not a tree.

However, a key principle during a survey is to have complete trust in the person being interviewed. It's not about looking for the lie, but the truth. If you notice details missing, ask questions. Learn to listen to what Not was said to find out what indeed was said.

The gardener's broomstick story

An example of a story without details comes from an investigation I conducted a few years ago. At that time, a gardener reported his wife to the police as missing. It was a beautiful summer day in June, the gardener had lay down at four in the afternoon for about half an hour and then found that his wife had disappeared. However, the gardener did not appear at the police station until ten o'clock in the evening. When questioned, I asked him the following question: "What did you do between four o'clock and now?" He replied that he had done nothing. He hadn't made up any details for his story. The gardener only had a broomstick to show his story and that gave him away: We found out that he had really murdered his wife.

Realize the truth

Any fool can tell the truth. However, you have to be very astute to tell a convincing lie and to convince an investigator that a broomstick is a tree. Put yourself in their shoes and trust them completely instead of assuming they are lying. An investigator must keep these five things in mind:

  • Go to the scene
  • Don't talk, just listen
  • Don't make any guesses
  • Focus on body language
  • Search for the truth

An investigation is not about exposing a lie, it is about finding out the truth.


Do you find this an interesting FRAUDtalk?
The next FRAUDtalks conference will take place
on September 25th in Amsterdam.

Buy your ticket here