Previously we discussed a few deception detection methods based on biometric and behavioral indicators. To recap, we established that such methods are not independently reliable for knowing when a subjecting is lying, but that they can be successfully employed to help with development of approach strategies. While it is important to know when someone is attempting to deceive you, it is not always important that the subject admit the deception. It depends entirely on the reason for the interrogation and the context of the deception. Behavioral and biometric assessments represent a facet of deception detection. Another aspect is direct evaluation of the information provided in the context of previously known information.
In any interrogation there will be known data related to the subject and the event(s) in question; otherwise, there would be no interrogation taking place. In a law enforcement aspect, there will be some evidence that leads the police to believe the suspect is somehow connected to a crime. In an intelligence interrogation, the detainee was generally detained for activities or information linking him to enemy activities of some sort. There will also be information on the subject’s person (referred to in the military intelligence interrogation lexicon as pocket litter) in any context that will provide some insight about who the individual is and how they might be connected to a particular activity, event, or group. All of this information can be used in the conjunction of a questioning plan to evaluate the veracity of the subject’s responses. For example, a subject might claim no knowledge of a particular event, while the interrogator knows there is direct evidence of their presence when the event took place. Or, a subject might claim to have no contact with a known individual, but his cell phone records show that they have routine contact. Keen knowledge of the available evidence is the first and most important (and simplest) step in correctly assessing the veracity of the subject.
The employment of repeat and control questions are another technique for identifying deception when dealing with a subject. Repeat questions seek to identify inconsistencies in the subject’s story by inserting subtly reworded questions seeking the same answers at different points throughout an interrogation. Control questions inquire after know pieces of information to determine whether the subject intends to deliberately mislead the interrogator. Internal inconsistencies discovered through repeat questions and inconsistencies with known information discovered through control questions are likely indicators of deception, but as with other methods the interrogator cannot assume with certainty that an inconsistency is a lie. The interrogator must take into account cultural differences that might cause a subject to be confused about what is being asked. In the case of an unexpected response to a control question, there is always the possibility that known holdings on a particular topic could be incorrect. The interrogator must also account for inherent biases in the construction of questions; if an interrogator is not cognizant of personal biases then the interrogators’ questions might be deliberately confusing, eliciting seemingly deceptive responses. All pitfalls are exacerbated by the use of an interpreter. (Interpreters present a panoply of concern worthy of separate discussion.)
Other indicators include inconsistency between a person’s asserted position or role and the information they provide, such as a detainee claiming to be a mere private in a foreign military, yet being able to answer questions related to an insurgent group’s strategic intent. Similarly, a subject’s inability to use technical language consistent with his claimed role or expertise (or vice versa) may indicate deception. A subject providing information on events that are inconsistent with a previously established timeline or providing detailed accounting of certain periods of time but only vague recollections for critical periods of time are also indicators of deception. Stories that sound rehearsed, such as detailed recollections of an event that have no variation when reported by the subject at different times or in different contexts may also demonstrate untruth. Again, no one indication makes it certain that the subject is lying; and interrogator must look for multiple indications over a period of time, and constantly assess the plausibility of a subject’s explanations.
How to react to deception is a different matter. In a law enforcement context it may be very important that the subject admit to a specific role or action for use at trial. In an intelligence interrogation such confessions are generally less important or completely irrelevant.
When employing control questions, it is normally part of the overall strategy to challenge the subject on inconsistencies, even if they are ultimately not of significance. The goal is control, so it may be useful in terms of the long-term strategy for cooperation that the subject knows you know about the deception. The intent is to make the subject believe that deception is futile. In some cases it is not worth the time and effort to attempt to convince a subject to admit deception; the interrogator simply reports the deceptive behavior with any information provided to ensure the claims get the proper scrutiny. As previously discussed, it is never a good idea to take information gathered through interrogation at face value; additional vetting is always required.
In summary: Deception detection is art, not science, and no single technique is 100% reliable. A broad strategy for assessing truthfulness is always warranted, and needs to focus on behavioral deviations while using known data as a control. It is not always necessary to get a subject to confess to deception; it is sufficient to recognize and control for possible deception when reporting findings. Any information gather should always be vetted against known holdings and any capabilities to acquire new information to confirm or confute.
Identifying and responding to deception is normally a part of the overarching approach strategy. We’ll discuss those in a future installment.