From: jcs
Detecting deception is a crucial aspect of criminal investigations, often employing specific questioning techniques and technological tools like polygraph tests. Detectives utilize various strategies to elicit truthful responses and identify inconsistencies in a suspect’s statements [00:00:28].
Behavior-Provoking Questions
One common technique is the behavior-provoking question, designed to elicit different responses from innocent versus deceptive individuals [00:00:28].
- Innocent Person’s Response: An innocent person typically gives a “draconian response,” immediately suggesting the harshest possible sentence for the crime they are falsely accused of committing [00:00:32].
- Deceptive Individual’s Response: A deceptive individual often provides an “equivocating response,” fragmenting or diverting from the question to avoid a direct answer [00:00:41].
Example of a behavior-provoking question:
“When we find the guy who took them, what do you think we should do?” [00:00:21]
In response to this, an innocent person might suggest “life in prison” or even the death penalty if the victims are not alive [00:01:02].
Identifying Inconsistencies and Lies
Detectives also look for inconsistencies in a suspect’s narrative and utilize information they already possess to expose deception. For example, in a case involving marital infidelity:
- An interrogator confronted Chris with knowledge of his cheating, despite Chris’s “boldface denial” [00:02:30]. Chris had denied ever cheating on his wife, and claimed to suspect his wife had never cheated on him either [00:02:22].
- The interrogator used Chris’s recent physical fitness as a subtle hint that he might be cheating, stating, “you can imagine when guys start cheating or want to cheat, that’s what happens” [00:03:12].
Digital Forensics
Investigators can use specialized programs to recover every piece of digital exchange sent from a device, even if it has been long deleted [00:02:53]. This means that deleting correspondence, as Chris likely did with his mistress, will not prevent law enforcement from accessing it [00:02:46]. This is a vital investigative technique in crime investigation.
Polygraph Testing as a Deception Detection Tool
Polygraph tests are a key tool in police interrogations for detecting deception [00:10:00]. The polygrapher aims to create a “heightened state of anxiety” in the suspect to make it harder for them to deceive the test [00:10:44].
Pre-Test Phase: Psychological Pressure
During the pre-test phase, the polygrapher applies psychological pressure disguised as reassurance [00:10:30]. This is common when the suspect’s guilt is almost conclusive [00:10:39].
- Amplifying Anxiety: The interrogator will amplify the suspect’s anxiety before the polygraph, suggesting that “everyone” thinks they might be involved [00:07:09]. They predict the suspect’s thoughts that night, implying they will regret not telling the truth [00:07:48].
- “Psychological Pressure Disguised as Routine Questioning”: The polygrapher might ask the suspect to describe ways to make someone disappear or commit murder, ostensibly to ensure they understand the questions on the test [00:13:56]. This forces the suspect to mentally confront the actions they are accused of.
Directed Lie Polygraph Test Structure
The “directed lie polygraph” test involves three types of questions [00:18:04]:
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Known Truth Questions:
- Purpose: To establish a baseline reading for when the subject is telling the truth, eliciting minimal bodily responses [00:18:27], and to disconnect thought patterns between questions for more accurate readings [00:18:38].
- Examples: “Are you sitting down?” or “Are you wearing shoes?” [00:18:22]
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Control Questions:
- Purpose: The subject is instructed to purposely lie to these questions, usually starting with a phrase like “before 2018” [00:18:44]. These questions are constructed so that any answer would be “no,” making it easy to lie [00:18:56].
- Example: “Before 2018, did you ever lose your temper with someone you cared about?” The expected answer is “no,” which is a lie [00:19:19].
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Relevant Questions:
- Purpose: These questions directly relate to the crime under investigation, and the examinee is expected to answer truthfully [00:19:01].
- Deception Indication: A guilty subject will show a much stronger physiological reaction to the relevant questions than to the control questions, even if they are lying on both. This is due to the immediate threat posed by the relevant questions [00:19:09].
- Example: “Did you physically cause Shanann’s disappearance?” [00:21:50]
Polygraph Test Results and Interpretation
Before the real test, the polygrapher may give an initial compliment to boost confidence, then abruptly reveal that the subject is a “really bad liar” based on their reactions to the control questions [00:20:01]. This feedback emphasizes that the subject’s body shows significant reactions when they lie, which will be “even 10 times more amplified” for significant questions about the crime [00:20:56].
After the full test, the polygrapher will inform the subject if they “did not pass the polygraph test,” clearly indicating that they were not honest [00:23:32]. This leads into further interrogation and pressure for a confession.