Forensic Polygraph in Crime Investigation: A Case Study

Abstract

A polygraph is an instrument that measures and records physiological changes inside the body. In the absence of a valid physical evidence, polygraphy may be a useful technique to verify truthfulness or detect deception. The present study was conducted to determine the truthfulness of a suspect in a murder case that was referred to PFSA for a polygraph examination. The stomach contents of the examinee and the hyoid bone of the vicvtim were submitted to the department of toxicology and forensic pathology at the PFSA, respectively. In the present study, integrated zone comparison technique (IZCT) and forensic assessment interview technique (FAINT) designed for specific and multi issue testing were used to examine the suspect. Computerized Academy for Scientific Investigative training (ASIT) Algorithm and weighted scoring were applied in IZCT and FAINT scoring, respectively. The suspect of this murder case was brought to PFSA for polygraph examination. During the initial interview, the suspect denied any involvement in the said case. However, after complete polygraph examination, the suspect was proven to have been deceptive and later on confessed to police officials. The polygraph examination of the suspect proved him deceptive which was later confirmed by his confession. His stomach did not contain any toxic/ sedative material.