Blue Line

Teaming up to detect liars

September 4, 2014  By Normand Borduas

Police have used polygraphs for decades to establish guilt, involvement or innocence of suspects.
Unfortunately, the examination often is done at the end of an investigation, after all other means have failed, and the suspect must agree to take the test for it to be useful.

Knowing that a large portion of polygraph tests carried out by police involve innocent people, it’s no surprise that tools have been developed to help police get an edge at the start of an investigation.

Many guilty subjects will not show up for a polygraph examination, often on the advice of their lawyer. They don’t want to chance not “beating” the test.

“Research on indicators of deception from demeanour have not been given much systematic attention, even though some of them might yield measures of comparable or perhaps greater accuracy than the polygraph,” the National Research Council stated.


Considering the limitations of the polygraph test, I’ve been working toward developing a method to help detectives in lie detection in the early stages of their investigations – “the TEAM approach.”

As a detective-sergeant for the past seven years, I have been spending a large portion of my time in Montreal interrogation rooms. Every case I encountered offered a different challenge in lie detection, mainly because, as research has shown, people hide their lies in different ways. It became obvious that detecting them is a lot harder than I originally thought.

I rapidly developed an interest in lie detecting tools and was able to get training in forensic interviewing at the Canadian Police College. This included statement analysis and Synergology (lie detection using nonverbal cues) and video interrogation at École Nationale de Police du Québec. It was a real eye opener on how to detect deceit.

Former polygraph examiner Neil Barker taught the course and offered an interesting point of view. “How many tools to detect deception will I use to determine the subject’s truthfulness?,” he would ask himself while investigating a case.

Sometimes, the facts allow an officer to quickly identify potential suspects and deceptive subjects. In other situations, such as physical child abuse cases, you may have several potential suspects. Identifying the most probable is then paramount to determining the investigation’s direction. If a detective can identify a perpetrator amongst a series of suspects with seemingly equal potential, the next decision could break the case wide open.

Detectives often rely on their gut feeling in the early stage of an investigation. Few investigators are properly trained in methods of lie detection such as Scientific Content Analysis (SCAN), Reality Monitoring (RM), Criteria Based Content Analysis (CBCA), Synergology (from Philippe Turchet), Behaviour Analysis Interview (BAI) or micro expressions from Eckman’s studies. An investigator’s experience and impression about an individual will often be the only guide in judging a person’s truthfulness. They will be correct about 50 per cent of the time, the same as a layperson.

One major advantage of using lie detection tools are that they can be used without the suspect’s knowledge or consent.

Different investigators using the tools might come to the same conclusion about a subject’s truthfulness, for different reasons. Each officer may interpret verbal and non-verbal signs of deceit in varying ways. Some may place a greater emphasis on certain cues used to detect lies, where others might find them less conclusive.

I became conscious of my own limitations and biases when I faced difficult challenges in cases and began looking for ways to adapt my training and experience to get better results in evaluating the people in front of me.

I developed an approach to lie detection to improve the likelihood of correctly determining whether an individual was being honest. “TEAM” – Target, Extract, Analyze and Maintain – also illustrates the concept that we are taught as young police officers: “working in a team makes us better and stronger”.

To be effective, lie detection must be done by a team of two or more experienced investigators. Tunnel vision is the worst enemy. The help of a partner to confirm or dismiss analysis of the lead detective helps alleviate any biases.

I assembled a team in Montreal to prepare and conduct the interrogation of a suspect in major child abuse cases. Included were forensic psychologists, a Sûreté du Québec criminal profiler, polygraph examiners and experienced interrogators from our investigative unit. The results exceeded our expectations. Each member’s expertise offered a different perspective on the problems that arose during the preparation and suspect interviews.


The major difficulty in assessing if someone is lying is to identify where or when they lied. Many deceptive people will embed their lies in a large truthful statement. Lie detection tools like SCAN, RM, CBCA, BAI or Synergology may be useful at this point to pinpoint lies. The more tools you use, the more effective you become at separating fact from fiction. Only when you match the verbal response with the non-verbal behaviour do you get a complete portrait of the statement.

Take, for example, a man being interviewed for physical abuse on his child. The beginning of the interview usually consists of building rapport with the subject. Then, a detective will ask more direct questions about the accusations. Do not conclude anything from only one gesture when observing a suspect.

On the other hand, a combination of several body movements or a change in behaviour may provide very good clues on the suspect’s truthfulness or deception. For instance, a change in position on a chair, hands disappearing under the thighs, scratching of a certain body part or crossing arms or legs can all serve to illustrate deception at times or a change in willingness to cooperate.

To identify those changes, an investigator needs to assess the suspect’s baseline behaviour. This would usually be done during the non-accusatory phase, when preliminary information is sought about the individual and the issues discussed are non-threatening for the subject. Combining Synergology (the study of non-verbal behaviour) with a criterion such as “quantity of details in a statement” from the CBCA list, will significantly improve accuracy in differentiating lies from truths.

Research has established that a truthful statement will contain more details than a deceptive one. Analyzing body language while a person gives an account of the event (with or without sufficient details) will provide useful information to evaluate the subject’s statement. Because Pinocchio’s nose exists only in fiction, combinations of non-verbal changes and verbal cues are essential to draw any type of conclusion.

A combination of two verbal tools of detection is also another good way to improve the likelihood of detecting deceit and truthfulness. For example, combine the criterion contextual embedding of the CBCA list with spatial and temporal details of the RM list.

The CBCA criterion is more general and described as placing the story in a time and place in connection with a habitual activity. The RM criterion adds the spatial and temporal details of the events that have been found to be relevant in differentiating truthfulness from deceit. Research has shown that a combination of tools will improve the accuracy rate of police officers in evaluating the truthfulness of a statement.


The next step is to extract information. Knowing where and when deceptive suspects are lying is the first step toward convincing them to tell you the truth. No less difficult, extracting the truth from an unwilling suspect poses many challenges. Several interviewing techniques can be used but an investigator must appear genuine and build a rapport with the subject. Many police manuals offer different alternatives in interviewing to obtain a confession and officers adapt them to their own personality.

One of the most effective ways to extract the truth is tactfully questioning a suspect. Some techniques will suggest introducing evidence in bulk or at the end of an interview. When a tactical approach is used, the evidence against the suspect is carefully introduced only when required and necessary.

Whether the case has lots or little evidence to incriminate, careful planning of the introduction will insure that only the required information is provided in order to convince a suspect to admit guilt. Present too much proof and you risk shutting a suspect down and making them feel there are no advantages to confess.

On the other hand, present too little evidence and suspects might not feel the need to tell the truth, believing that police don’t have much on them. The truth resides in the details and effective questioning techniques are the key to identifying discrepancies and obtaining sufficient details that might force them to change their version and finally tell the truth about events.


Not all facts are known at the early stages of most investigations. Once you identify an area where you believe a suspect is lying and persuade them of this, you still need to verify whether they told you the truth or more lies (this may come later in the investigation through warrants, additional statements from witnesses or co-accused).

The analysis is sometimes an ongoing process during the interview. New evidence coming in from ongoing search warrants, for example, should be provided to the officer conducting the interview. This new information is contrasted with the statement the suspect has provided. The officer will then adjust questioning accordingly. This will prevent the individual from making a false confession that would go undetected. Later in court this analyses will also serve to establish that the subject is now telling the truth about involvement in the case, since it is supported by the facts subsequently acquired.

Famous wrongful convictions cases in Canada and the US involved incriminating statements by suspects that were not later matched with the facts of the case or were not validated. The importance of hold back evidence is essential to protect the investigation and validate an accused’s statements. This consists of facts known only by certain police officers on the case, the victim and the accused. Withholding such evidence from the public or people outside the “need to know circle” will allow police to identify a false confession, verify a truthful one or incriminate others.


Lastly, officers must maintain their relationship with the suspect at the closing of the interview, keeping in mind that they have confessed their involvement in the case. For this to happen, as mentioned earlier, rapport had to be built.

At the interview conclusion, irregardless of whether the suspect confessed, the rapport must be maintained. No one can predict when (or if) a suspect might want to sit down again to provide police with further information about the case (confess) or become an informant.

Maintaining the same professional attitude from start to finish will signal interviewees that your openness doesn’t end with the interview and they might be more inclined to come clean at a later date.

Lie detection is a difficult task and not everyone is good at it. It takes training, practice and a methodology such as the TEAM approach to improve the chances of differentiating fact from fiction. Knowing where the lies are is useful. Even if a suspect does not confess it will guide a detective in their next course of action.


Montreal Police Det/Sgt. Normand Borduas specializes in investigative techniques training. A graduate of the University of Montreal, Quebec Police Academy and CEGEP John Abbott College, he is an expert in statement and video analysis. Contact him at for more information.

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