A polygraph unit monitors and records readings of the Sympathetic and Parasympathetic Nervous Systems when a person is asked a series of carefully designed questions while attached to the unit. The person taking the test is asked questions where they only answer yes or no. The examiner can determine if the person is giving a true statement by reviewing the readings.
The Indiana State Police Polygraph Unit underwent an inspection and review of their procedures and casework. This process includes the examination of every polygraph test being reviewed by another polygraph examiner before the results are considered official. The PLEA program is managed by local, state and federal polygraph examiners and the inspections are conducted by volunteer subject matter experts using mandated procedures.
The PLEA program ensures that law enforcement agencies that their polygraph programs are employing standardized practices that provide a level of service that is ethical, professional, and offers reliable results to the jurisdiction served.
According to the Indiana State Police, a polygraph test is used mostly in child molestation investigations. There are most cases when the act is reported after the incident occurs when no physical evidence is available so a polygraph is used for questioning.