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Forensic Science

Polygraph

Photo of Lab Subject Being Tested on the Computerized Polygraph

Lab Subject Being Tested on the Computerized Polygraph

Photo of Polygraph Chart

Polygraph Chart

There is no such thing as a lie detector. A well-trained polygraph examiner equipped with a polygraph instrument and sufficient facts of the case can determine if a subject's statements are truthful or deceptive with an accuracy of 95% or better.

The Polygraph Unit conducts examinations on police and civilian applicants of the Police Department. The Unit also conducts polygraph examinations on subjects in criminal investigations.

Polygraph examinations can be used in court if both parties to the case agree in advance. Sometimes during the examination process, when confronted with results that indicate deception, subjects may and often do confess.

The Interrogation and Interview Specialists conduct examinations in the laboratory or carry a portable unit into the field. All the polygraph examinations are now computerized with tracking of the heartbeat, respiration, and galvanic skin response. The computer will score the test and issue a report. It is the examiner, however, who must make the final call on the individual's truthfulness.