The polygraph examination is a credibility assessment process dating back to the 1920's. It utilizes Polygraph and Credibility Assessment (PCA) techniques to determine an individual's truthfulness and credibility. While NCIS recognizes the polygraph as an invaluable investigative aid, it is not a substitute for conventional investigative techniques.

The polygraph instrument records physiological activity: blood pressure, heart rate, respiration, etc. The polygraph examiner reviews a series of questions with the subject prior to the test. Subsequently, during the test, the same questions are asked several times in different order. The theory is that a person will produce significant and consistent physiological responses--indicated by the polygraph instrument--when answering deceptively to a question during the test. 

The NCIS Polygraph Services Division is comprised of highly skilled interviewers who utilize the polygraph to obtain information in support of criminal, counterintelligence, and counterterrorism investigations for NCIS, the Department of the Navy (DON), and the Department of Defense (DoD). They are often called upon to support the war fighter with real time tactical information. Additionally, the Polygraph Services Division administers the DON's Counterintelligence Scope Polygraph Program, helping to ensure that the DON's most sensitive national security programs are protected against the "insider threat."

NCIS Polygraph Examiners are either Special Agents or Security Specialists who have successfully completed the core curriculum (PCA Course) at the Defense Academy for Credibility Assessment (DACA), satisfactorily served a probationary period of 6-12 months, and have been officially certified by the Director of NCIS to conduct polygraph examinations.