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Investigation & Risk Management


Screening & Talent



William D. Evans, II Forensic Polygraph Examiner, JD, MS, A.C.P


Ken Butler


Mark Martin



Dennis Doverspike



Nancy K. Grant


Poly-Tech Associates, Inc.
Truth & Law Center
1185 South Main Street
Akron, OH 44301
P: 330.434.2344

4403 St Clair Ave
Cleveland, OH 44103
P: 216.241.4661

250 East Broad St.
Suite 200
Columbus, OH 43215

Accurate Polygraph Results

   Polygraph consistently attains a very high level of reliability and validity. Based on a number of studies, the accuracy in criminal investigations shows the reliability of these examinations to be very high. Depending on the study, test validity can reach 98%.

   Computerized polygraph instruments provide digitized (computer generated) physiological tracings. As a result it has no moving parts, as characterized in conventional analog polygraph equipment and it is very sensitive to the subtle physiological responses indicative of truthfulness or deception.

   Analog polygraph instruments are considered "conventional" equipment in the field of lie detection. The pens which scribe across moving chart paper record physiological responses from certain parts of the involuntary nervous system.

   The analog polygraph has been in use for several decades. The computer revolution made it possible for digital computerized instrumentation to be used, which also measures and records involuntary nervous system responses. Poly-Tech is capable of conducting polygraph examinations with either type of instrument.

   Since 1990, several case studies have been published regarding Polygraph accuracy which is dependent on several dynamics.

   • Polygraphist's education, experience and training
   • Quality of instrumentation, and how it is utilized.
   • Examination atmosphere
   • Exam criteria, including subject and issue of examination.

   Polygraph is the most widely accepted form of lie detection and can be admitted as evidence in court proceedings, by way of agreement and stipulation. Polygraph has achieved scientific acceptance, and having been admitted as evidence in Criminal and Civil cases at the Federal, State and Local levels.

Generally there are four types of examinations:


   • Court Admissible Testing through agreement and stipulation in conjunction with the Defense         and Prosecution.   
   • Confidential Testing generally used by Defense Attorneys to establish a clients veracity. Such         testing greatly assists in defense strategy.
   • Investigative Testing generally used by law enforcement to eliminate or isolate suspects in a           criminal investigation.
   • Pre-Employment polygraph screening for security clearance purposes generally used by public      service agencies in police and fire departments.

   Regardless of examination type, a waiver and release form is always signed by the person before being examined. This release form authorizes the polygraphist to proceed with testing. It also permits the results to be conveyed to persons that the person being tested specify as recipients of the results. (Since the testing is confidential, results are only released to certain persons specified by the examinee as recipients such as the examinee, lawyer representing the examinee, or other specified party.) The release / waiver form allows Poly-Tech and its polygraphists to proceed with such examinations / testing, while being released from liability flowing from the procedure, reporting, opinion etc.

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