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Detecting Deception

Tony T. Henrie

By Tony T. Henrie

In the legal profession, the gathering of accurate and reliable information, whether through research, investigation, or interview, is essential to the successful outcome of our casework. Proper evaluation of the source of any information, therefore, is integral to our work. Detecting deception during interviews assists investigators and attorneys in evaluating motivations of witnesses and subjects and the integrity of information they provide.

The interview, in its most basic sense, is simply getting people to talk to us. As they do so, they make decisions about whether they will convey truthful and complete information or deceive us by lying or omitting critical parts of the truth. These decisions are based on numerous factors, including their sense of right and wrong as well as what may best benefit them or others. Proper assessment of their motivations and information requires training and experience.

Multiple studies, of various levels of academic rigor, have shown that those who believe themselves to be good judges of character and good at discerning a lie are, in fact, no better at detecting deception than those who consider themselves to be poor at it. At one end of this spectrum, we have the skeptics, who simply disbelieve, despite any other evidence. At the other end are the believers, who desire to believe to the degree that they willfully disregard any other evidence. Both extremes have their strengths and weakness, and both character types are susceptible to deception. Most people fall somewhere in the middle. Either tendency may cause the interviewer to miss hints and indicators of deception during the interview. Both types may balance their natural tendencies by simply receiving information at its face value and applying measures to further evaluate it.

When a person finds him or herself in a critical situation, such as being the subject of an interview, involuntary functions happen in their bodies – adrenaline is released in the circulatory system causing heart and breathing rates to increase, they begin to sweat, blood circulation in extremities decreases causing cold hands and feet, and thought processes become focused and limited. These reactions vary in degree, depending on the individual’s natural body tendencies, their life experiences and their motivations. Prior successes in deceiving others may become a factor when one’s intentions are to deceive. These physical reactions are natural responses to fear. One who fears less will have less obvious responses. These physical responses cause changes in one’s behavior. These changes are our primary tool in detecting deception during interview.

The first principle of effective interviewing and detecting deception is to develop good rapport with the interviewee. This is done by creating avenues of discussion that present common ground between us and them. This should be non-threatening conversation that may have no relation to the topic at hand. This allows us to observe a baseline of normal behavior for this individual during this interview. That is to say, we note how the person sits, their posture, whether they have a nervous twitch, etc. We take note of how they make or avoid eye contact during conversation, their voice tonality, movement of their hands, facial expressions, etc.

As we broach the critical topic of our interview, we watch to see departures from this baseline behavior. Changes from the norm may be indicators of deception. For instance, if we are in the midst of a relaxed conversation with the interviewee and we change the topic to something critical to them, they may change their sitting position or move to a more attentive posture.

As the interview progresses and we see these changes, we may test their responses by asking critical questions. These are direct questions, such as “Did you do it?” or “Why did you go to the house?” the answers to which may be critical for the interviewee and also to our case. If we detect marked changes in their behavior from that which we established as a baseline, we may reliably determine that they are struggling with those involuntary physical responses mentioned above.

We may further test them by asking indicator questions. These are designed to elicit responses characteristic of truth or deception and may be adapted to the situation at hand. It is important to understand how these questions work and how to properly pose and interpret responses. For example, if a bank teller suspected of theft were asked, “If you didn’t take this money, who do you think took it?” an inexperienced interviewer might expect the liar to immediately cast blame upon a fellow employee. However, that would be in error. The liar will normally say he or she does not know, offering no attempt to help the investigation, while the truthful person will normally attempt to assist the investigator by naming an individual they believe could be a possible suspect. Poorly posed indicator questions or inaccurate interpretation of responses will result in an inaccurate evaluation of the truthfulness of the interviewee and the information provided by them.

The truthful person desires only to convey information during an interview as long as they feel they are believed. The deceitful person wishes to convince the interviewer of the truth of their statements from the beginning. This causes the truthful person and the liar to act differently during interview. A trained and experienced interviewer may detect these differences. While true detection of deception is complex and full of nuances, the application of some basic principles by the interviewer may be useful in evaluating motivations of the interviewee as well as the accuracy and integrity of the information they provide.

If effective interviewing is an art form, detecting deception is a fine technique within it and, indeed, is an art form in itself. Becoming adept requires training and experience, though it may never be fully mastered. The value of detecting deception in our profession is to lead us to further investigation and verification, so that we may base our casework on solid, accurate and reliable information.

Tony T. Henrie retired from the Federal Bureau of Investigation after 23 years as a special agent. During his tenure, he conducted investigations relating to drug trafficking, white collar crime, child pornography, violent crimes, fugitives and both international and domestic terrorism. He retired in 2012 as a supervisory special agent, having spent his last three years as an instructor of interviewing and interrogation techniques at the FBI Academy in Quantico, Virginia. He is currently the chief investigator for Bedrock Investigations, a branch of Bedrock Protection Agency in Salt Lake City, Utah.