Polygraphs and Missing Child Cases

When reading case after case of missing children and the investigations surrounding their disappearances, I have started to notice a common point of contention, which I am beginning to find is not a subject that is discussed solely about in a public forum very often.  So let’s discuss it.



While polygraph exams are not admissible in court in North America the majority of the time, there are exceptions to every rule, they are consistently used by investigators as tools to assist in cases in ways such as following up on leads, and ruling in and out persons of interest, just to name a few.  In Canada, the polygraph is regularly used as a forensic tool in the investigation of criminal acts.  The Supreme Court of Canada rejected the use of polygraph results as evidence in court.  While polygraph tests are commonly used in police investigations in the US, no defendant or witness can be forced to undergo the test. The U.S. Supreme Court left it up to individual jurisdictions whether polygraph results could be admitted as evidence in court cases. Nevertheless, it is used extensively by prosecutors, defense attorneys, and law enforcement agencies.

A polygraph (popularly referred to as a lie detector) measures and records several physiological indices such as blood pressure, pulse, respiration, and skin conductivity while the subject is asked and answers a series of questions. The belief is that deceptive answers will produce physiological responses that can be differentiated from those associated with non-deceptive answers.  In cases where the individual who will be undergoing the exam is in severe emotional distress, the emotional elevation becomes the baseline for the test, therefore maintaining accuracy.  Polygraph tests are solely conducted on persons who are mentally and physically sound. There are no accusations, simply questions answerable by “yes” or “no.” The examiner is neutral, which, according to the Euro Polygraf Center, enables the subject “to free himself of any prejudice in connection to his examination and of any external sources of stress.”  The chances of beating a polygraph given by a competent professional examiner with all the information, is slim to none. A person who is trying to beat a test might be able to produce charts that are hard to read but a competent examiner will know something is going on.

In missing children’s cases police must quickly work to rule out the family, including the child’s parents because statistics show that in most cases they are responsible for the child’s disappearance. They also must work to rule out people close to the family, including friends and relatives.  The process of eliminating those close to the missing child can be accomplished in a shorter amount of time if police have the cooperation of everyone involved.  Law enforcement will often ask parents or family members to submit to a polygraph exam to help rule them out and reach the truth on unclear matters.  The quicker law enforcement is able to rule these people out, the quicker they are able to focus on following other leads.

Many believe parents of missing children need to take a polygraph test no matter how emotionally upset they are.  It raises questions and suspicion when a parent of a missing child refuses to undergo a polygraph exam with the general feeling being that an innocent person would have no reason to refuse a poly.   Most parents will gladly take a polygraph exam, doing whatever they can to help find their child.

Personally, I feel a polygraph is a great investigation tool in these cases.  If nothing else, it can prompt a parent to divulge information they had not previously divulged.  Considering polygraph exams are not admissible in court, an innocent person really has nothing to lose.

There are many different views and points in this matter, making a clear cut answer regarding the validity and accuracy of the exams nearly impossible to be reached.


So now we would like to hear from you.  Where do you stand on the issue of using a polygraph exam in the cases of missing children?  Please take the poll below, and feel free to leave a comment.  We are very interested in what you may have to say.


~ by LTWH on November 22, 2011.

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