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Polygraph
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©2008 Article published in the free PATC E-Newsletter
Link to Article online: http://www.patc.com/weeklyarticles/polygraph-investigation.shtml
www.patc.com | www.llrmi.com | www.fsti.com | www.school-training.com | 1-800-365-0119
Investigator’s
Use of the
Polygraph
By Dan Sosnowski
Written for and Distributed by Public Agency Training Council, and PATC Partners and affiliates. For
duplication & redistribution of this article, please contact the Public Agency Training Council by phone
(1.800.365.0119), or by email (newsletter@patc.com).
Increasing population growth, crime rates and new resistance to expansion of community services have
all contributed to increased case loads for law enforcement.
The polygraph, when properly used as an investigative tool to eliminate the wrongfully accused and
identify the guilty, can provide the investigator with a more efficient and productive use of his case time.
Unfortunately, misunderstanding and misuse as to the polygraph’s role in the investigative process still
persist. The following is an attempt to describe the polygraph’s function in criminal investigations, its
limitations and some of the basic procedures recommended for an accurate and productive
examination.
POLYGRAPH PRINCIPLES AND PROCEDURES
Investigators should be aware that there are two primary applications of the polygraph in criminal
investigations; Diagnostic and Interrogatory. Diagnostic applications seek as their ultimate goal, a
successful determination of truth or deception.
Interrogatory polygraph is less concerned with the issue of truth and usually seeks a confession of
wrongdoing from the suspect. Diagnostic polygraph requires an examiner with considerable training and
education using carefully constructed questioning techniques that provide scientific analysis of data
while interrogatory techniques essentially use the polygraph instrument or even non-functioning boxes
with lights and wires as a prop to induce sufficient fear in the suspect so that his only recourse from
emotional anguish is confession. Diagnostic polygraph examinations have been admitted into court as
evidence, while interrogations using polygraph as a wedge to confessions frequently have been ruled as
inadmissible in court.
©2008 Article published in the free PATC E-Newsletter
Link to Article online: http://www.patc.com/weeklyarticles/polygraph-investigation.shtml
www.patc.com | www.llrmi.com | www.fsti.com | www.school-training.com | 1-800-365-0119
A rule that investigators may want to follow is to choose the polygraph examiner as if yourself were
going to be requested to submit to take an exam. As many of you have heard, the polygraph is only as
good as the examiner.
PSYCHOPHYSIOLOGY
The polygraph instrument records physical changes related to the autonomic nervous system, the socalled
involuntary physiological responses, and not just any change from the normal physical recordings.
These are involuntary controlled by various centers in the brain.
The psychological stimuli that activate these involuntary responses are two; The emotion of fear,
specifically fear of being detected in a lie and the consequences of being caught in that lie; and conflict
between what the untruthful subject knows to be the truth and his physical and verbal attempt to
portray the opposite.
TEST PROCEDURES
The polygraph examiner must be advised with relevant information pertaining to the case facts collected
during the investigation. The examiner will generally discuss the issues that will be covered on the
examination with the investigator. This is important in order to address the issue that the investigator
wishes resolved. The examiner may then massage this information in order to fit the technical
limitations and conditions that the proper polygraph technique requires.
At this time, certain procedural issues should be addressed and resolved. These issues would include
who is authorized to receive the results? Who will be allowed to view the test? Is the subject in custody
and if so who will transport him to the testing facility? How will custody be maintained? Will the reading
of Miranda be required? If the subject is a juvenile, who will accompany this minor and sign the
necessary release forms? Is the subject represented by counsel? Will counsel be allowed to be in the
polygraph suite? Will the polygraph procedure be audio or videotaped?
At the time of the actual test, the subject will be required to read and sign the necessary release forms.
These forms state that the subject has agreed to submit to the test and the results of the test can be
made available to the requesting agency and any other parties that are involved in this process. If the
test is being conducted on behalf of a law enforcement agency, the subject should be read his Miranda
Rights and no person should be tested without their consent. Other release forms are generally filed out
at this time. These forms will include their permission to audio or videotape the session, forms that deal
with their medical information and any other forms that the examiner may need to assess the subject’s
overall well being.
The examiner will then conduct a pretest interview with the subject in order to determine the facts and
circumstances as they are known to them. This affords the subject the opportunity to explain their side
of the story. During this phase, the examiner is also assessing the subject’s overall suitability to be
tested. This area would include the subject’s mental, physical and emotional state at the time of the
©2008 Article published in the free PATC E-Newsletter
Link to Article online: http://www.patc.com/weeklyarticles/polygraph-investigation.shtml
www.patc.com | www.llrmi.com | www.fsti.com | www.school-training.com | 1-800-365-0119
test. In some cases, the examiner may determine that the subject is not suitable for polygraph testing at
this particular time. The examiner may reschedule the polygraph for a later date depending on the
issues revealed during the pretest.
During this phase, the examiner is also allowing the subject to clarify or expound on any previous
statements made. The examiner will generally ask a series of questions that are designed to draw out
the subject’s verbal and non-verbal behavior. Information is developed regarding the subject’s overall
feelings regarding the issue under investigation. During this phase, the subject will offer explanations or
make statements which may later prove to be useful during the resolution phase.
©2008 Article published in the free PATC E-Newsletter
Link to Article online: http://www.patc.com/weeklyarticles/polygraph-investigation.shtml
www.patc.com | www.llrmi.com | www.fsti.com | www.school-training.com | 1-800-365-0119
The Truth about Lying
How to Spot a Lie & Protect Yourself from Deception
By Stan Walters “The Lie Guy”
Available at www.patc.com
Communication skills can make a big difference in whether people tell you the truth or
not. Knowing when to ask the next question, the behaviors that signal when the whole
story isn’t being told and what questions to ask can help you cut through deception and
lying so you can have confidence in your communications.
Based on the same methods used by law enforcement professionals, but appropriate
for everyday interactions, these skills and techniques can be applied in almost every
situation:
• hiring a nanny or household worker
• working with an employee
• talking with a service provider
• dealing with a teenager
• communication in a romantic relationship
Without threats or intimidation, Walters’ strategies will improve relationships and
communication by teaching how to spot a liar and, more importantly, how to get to the
truth. See how you can learn the same skills used by world's best interviewers to crack
to the toughest criminal and terrorists.
