Detecting Deception

By Joe Navarro, M.A. 
Stock image of an interview. ©

Throughout their careers, law enforcement officers must face the challenge of determining when someone is lying or hiding information.1 As researchers have demonstrated, this task can prove difficult. Most people have no better than a 50/50 chance of detecting deception.2 Increasing these odds requires preparation and skillful execution.


Skill Development

Some people say that chance favors the prepared mind; this holds true in life, particularly in law enforcement. Just as officers must stay abreast of current case law and best practices, they also need to remain aware of the latest research on nonverbal communication and deception.

The literature on body language and deception detection continually evolves. Unfortunately, officers rarely receive advanced education in nonverbal communication after they leave the police academy. Some will study it on their own, and others may read an occasional article. However, instruction in communication rarely is emphasized the same way as legal or firearms training. This is regrettable because law enforcement officers collect information through awareness and interpretation of behavior.

By developing skills in observation and lie detection, officers enhance their job performance and guard against the wrongful assignment of guilt to someone who merely is nervous or anxious.3 As important as it is to detect deception, it is just as vital for officers to determine the truth. DNA exonerations over the last 10 years have shown that in cases where subjects later were cleared, officers mistakenly attributed nervousness and anxiety to lying and culpability and did not realize that claims of innocence actually held true.4

Interview Setting

While an officer’s skill is important for detecting deception, so are the setting and environment. Obviously, not every interview is conducted under perfect conditions; however, if officers understand those circumstances, they can prepare better to achieve that idyllic situation. Polygraphers know the ideal surroundings for conducting a forensic interview. They give polygraph examinations in a quiet area with only the interviewer and subject present. 


The most advantageous way to conduct an interview is in a quiet room with no distractions or time restraints. The space should have only two chairs and a small side table for the interrogator. The interviewee ideally will sit near the door (less psychological stress), in the open and with no barriers. This way, the interviewer can observe the subject’s whole body at all times. Investigators should have the freedom to move around the room and adjust their seating position as necessary.

Psychological Comfort

The key to detecting deception is enabling the interviewee to relax by using traditional methods, such as rapport building. Establishing this relationship creates psychological comfort.5 When this is accomplished, the interviewer can ascertain baseline behaviors for later comparison, ensure optimal recall, and diminish the subject’s capacity to resist or argue. It also demonstrates to the court that there was no coercion or mental pressure. When it comes to deception, determining these baseline behaviors through psychological comfort is essential.

Effective Communication

In some respects, interviewing entails nothing more than “effective communication with a purpose.”6 In a forensic setting, investigators search for information with general investigative value or something that may prove their case. That constitutes the purpose of the interview.

Mr. Navarro, a retired FBI special agent with the National Security Division’s Behavioral Analysis Program, currently is an adjunct professor at Saint Leo University in Saint Leo, Florida.
Mr. Navarro, a retired FBI special agent with the National Security Division’s Behavioral Analysis Program, currently is an adjunct professor at Saint Leo University in Saint Leo, Florida.


Communicating effectively includes both verbal and nonverbal messages. It means that interrogators must ask questions properly so as not to arouse behaviors that mask true sentiments. When an interviewer becomes suspicious of a statement or begins to accuse a suspect, a negative emotional response usually results—the kind most people feel when someone blames them for something. When stimulated this way, the interviewee’s emotional state and nonverbal behavior become altered, masking true sentiments.7 This affects the innocent, as well as the guilty.

If investigators ask questions with curiosity rather than suspicion or animosity, they will notice the suspect displaying nervousness, tension, stress, anxiety, fear, apprehension, concern, or dislike as a result of the substance of the question, rather than the tone. This proves critical to detecting deception because the interviewer’s tone, attitude, demeanor, intensity, and manner all affect the emotions of the interviewee. It is better to be curious than accusatory. Once interviewers cross that line, the suspect’s behaviors result from emotions, not guilt.

Fortunately for investigators, not all words have the same weight to the guilty. A killer who used an ice pick may react differently if asked about a machete, knife, or gun. Those words may not have the same effect because only the mention of the specific murder weapon holds any kind of threat.8

When the suspect with guilty knowledge hears a question, survival instincts kick in, body movements can become restricted, and psychological discomfort may result. Interviewers may observe these reactions as body tension, a furrowed forehead, immobile arms, disappearing or tense lips, and distancing by leaning away. At the same time, this person initiates pacifiers—any tactile self-touching, such as stroking the face, biting nails, licking lips, wringing hands, or tugging at clothing —to relieve stress.


As most parents know from caring for an infant who does not speak, the brain responds to the world around it in real time, which allows people to see or sense what others think or feel.9 However, each person physically responds differently to stressors. Some people show stress by excessively sweating, vigorously massaging their neck or forehead, blocking with their eyes, ventilating their shirt, or tightly grasping their legs. More subtle persons swallow hard, compress or lick their lips, conceal their neck dimple with a hand, or cover their thumbs with their fingers. Over 215 identified behaviors associated with stress and discomfort provide clues as to how a person feels when asked a question.10 Fear, guilt, shame, and excitement cause emotional responses that most people cannot control. These provide insight during the interview process.

Four viable opportunities allow investigators to detect when a person hides something, feels anxious about a question, lies, or has knowledge of guilt. Once the interviewer is prepared, the ideal setting is arranged, and psychological comfort is reinforced, the interview process can begin.


When Asking

The first opportunity to detect deception arises when the interrogator asks a question. As the subject hears questions, the officer should look for behaviors that indicate restricted body movement (the freeze response, the first reaction to any threat), negative affect (chin withdrawal or compressed lips), or self-soothing (hand-on-body touching or massaging). A proficient interviewer asks questions and observes without being intrusive, showing doubt, or displaying suspicion. Investigators should look for any sign of discomfort, nervousness, or pacifying as they ask their questions.

While Processing

Interviewers have a second chance to gauge for deception when the interviewee processes the question. Some people quickly think things over, while others take their time. Regardless, the interviewer is looking for the effects of processing the question. For example, interrogators should watch for actions, such as the suspect repeating the question (a delay tactic, perhaps), seemingly troubled by the question, hesitating, or appearing to think deeply and carefully (sign of a cognitive load). Other behaviors to note include interviewees suddenly locking their ankles around the legs of their chairs; looking straight ahead, frozen in their seats; or darting their eyes, looking for an answer. These observations are important because changes in behavior or facial expressions mean adjustments in thinking, processing information, or feeling emotions. If a subject struggles with or appears troubled by a question, the interviewer needs to determine the reason.

When Answering

The third occasion to assess for hidden information, deception, or guilty knowledge is when the interviewee answers the question.11 The interrogator should note if the person gives the response with conviction, without hesitation, with an unwavering voice, or with confidence. Interviewers can watch to see if suspects respond passively, use a quiet voice, limit how much space they take up, or pacify themselves.

Other conduct by the subject might include answering with palms up (wishing to be believed) or palms down with fingers spread (dominant confidence display). They may reply with one shoulder slowly rising toward the ear, indicating weakness, doubt, insecurity, or lack of confidence. Their voices may crack, trail off, or change to a higher pitch, signifying important issues to explore. These tendencies indicate the need to look closer at the individual and determine why these behaviors exist.

“…law enforcement officers collect information through awareness and interpretation of behavior.”

After Responding

Investigators have the fourth opportunity for assessment after the suspect answers a question. At that point, a skilled interviewer will wait and watch for 2 to 4 seconds, creating a natural but pregnant pause to observe the interviewee. A number of behaviors revealing knowledge or guilt may present themselves after a subject responds to a question. Suspects may move or shift around (wiggle), create distance (move the chair or lean away), conduct cathartic breathing (long exhale), self-soothe (massage their shoulder or leg), wipe away sweat, or perform other actions to relieve the stress resulting from hearing, processing, and answering the question. These discomfort behaviors speak volumes to the investigator.

Additional Considerations

After making the proper observations during these four phases, it proves useful to remember that speech errors, hesitation, lack of confidence, indicators of stress, and pacifiers in relation to a question merely suggest some cause. They indicate that a stimulus (the question) has created stress and that something is there to pursue, much as in a polygraph exam.12 Investigators must remember that stress indicators do not conclusively indicate deception. As one nonverbal communications expert has said, “Unfortunately, there is no Pinocchio effect” when it comes to deception.13

Law enforcement officers must recognize the limits of lie detection. Deception can be identified only when all information is known, which usually is not the case. To guide them in their inquiries, investigators look for cues of discomfort or lack of confidence. If unknown issues or hidden information cause stress, interviewers must ask why. They should ascertain if the suspect is involved, lying, or not telling the entire story. Investigators should pursue all questions that indicate issues. A polygrapher cannot say definitively that persons have lied, only that they displayed indicators of stress when asked a question. Unfortunately, the same holds true for interviewers. That does not mean that interrogators stop asking questions. The interviewee’s discomfort or lack of confidence during questioning compels knowledgeable investigators to look further.


Reliable indicators of deception presently may evade interviewers; however, law enforcement can look for signs in a suspect’s verbal and nonverbal language that may indicate issues or deception. Interviewees’ behaviors help investigators identify knowledge, guilt, deception, issues of concern, or concealed information. The author’s experience teaches that during questioning, interviewers have four viable opportunities to look for these clues—valuable indicators that professional interrogators can use to determine the truth.

“Four viable opportunities allow investigators to detect when a person hides something, feels anxious about a question, lies, or has knowledge of guilt.”


1 The author bases the information in this article on his expertise and experience.

2 Paul Ekman, Telling Lies: Clues to Deceit in the Marketplace, Politics, and Marriage (New York, NY: W.W. Norton and Co., 1991), 162; and Aldert Vjrij, Detecting Lies and Deceit: The Psychology of Lying and the Implications for Professional Practice (Chichester, England: John Wiley and Sons, 2000), 5-31.

3 Saul M. Kassin, “True or False: I’d Know a False Confession If I Saw One,” in The Detection of Deception in Forensic Contexts, ed. Pär Anders Granhag and Leif A. Strömwall (Cambridge, UK: Cambridge University Press, 2004): 172-194; and Saul M. Kassin, “A Critical Appraisal of Modern Police Interrogations,” in Investigative Interviewing: Rights, Research, Regulation, ed. Tom Williamson (Devon, UK: Willan Publishing, 2006): 207-227.

4 Joe Navarro, “Detecting Lies vs. Detecting Truth: Serious Implications,” Psychology Today, 2011, (accessed June 4, 2011).

5 Joe Navarro, What Every Body is Saying (New York, NY: Harper Collins, 2008), 210-212.

6 John R. Schafer and Joe Navarro, Advanced Interviewing Techniques (Springfield, IL: Charles C. Thomas Publisher, 2010), 8.

7 Navarro, 2008, 210-213.

8 Navarro, 2008, 21-29.

9 Mark G. Frank, “Thoughts, Feelings, and Deception,” in Deception Methods, Motives, Context and Consequences, ed. B. Harrington (Palo Alto, CA: Stanford University Press, 2009), 55-73.

10 Joe Navarro, Clues to Deceit: A Practical List (Tampa, FL: A & A Printing, 2011).

11 Bella M. DePaulo and Wendy L. Morris, “Discerning Lies from Truths: Behavioral Cues to Deception and the Indirect Pathway of Intuition,” in The Detection of Deception in Forensic Contexts, ed. Pär Anders Granhag and Leif A. Strömwall (Cambridge, UK: Cambridge University Press, 2004): 15-40.

12 Charles V. Ford, Lies! Lies! Lies!: The Psychology of Deceit (Washington, DC: American Psychiatric Press. Inc., 1996), 221-235.

13 Mark G. Frank, 2009.