The Polygraph Unit is a component of the Criminal Investigations Division, which provides investigative support to the entire force. The function of the polygraph instrument (commonly referred to as the “lie detector”) is to determine the truthfulness or deception of an individual’s statement to police. The unit is staffed by one trained polygraph examiner.
During a polygraph examination, physiological data is collected from at least 3 systems in the human body. The sensors usually measure breathing rate, perspiration, and pulse or blood pressure. The examiner asks a series of questions to the subject. The subject’s physiological activity is recorded by the polygraph instrument while the subject listens to and responds to the questions. After questioning, the examiner reviews the physiological charts to determine whether or not the subject was being truthful. In general, a significant change (such as a faster heart rate, increased perspiration or faster breathing) indicates that the person is lying.