Southern States - Kerala-Thiruvananthapuram   

Crime Branch to rely on lie-detector tests

By G. Anand

THIRUVANANTHAPURAM July 21. The Crime Branch of the State police department has set up a full fledged polygraph unit at the Forensic Sciences Laboratory (FSL) here for conducting "lie detector tests'' on suspects in crime cases.

Recently, the Crime Branch had conducted the polygraph test on two persons being investigated in connection with cases of murder. The polygraph detected that one of the candidates, who is a key suspect in a murder that was committed in Kollam district several years ago, was concealing crucial information regarding the crime.

``The subject has tested positive. Armed with the polygraph evidence, we are viewing the case in a new light. There should be a breakthrough soon'', an official said. In the second case, the suspect had tested "negative''. The polygraph equipment is now being housed in an air-conditioned sound- proof room at the FSL.

Though the courts in India are yet to accept a polygraph test result as a conclusive evidence like a finger-print, there have been several cases in which the "lie-detector'' test has been accepted as secondary or corroborative evidence. Recently, the Karnataka High Court had accepted polygraph test result as evidence in a murder case, a lawyer pointed out.

The Crime Branch is of the view that charge sheets backed by polygraph test results and other scientific evidence will ensure a higher conviction rate in cases investigated by the agency. "The polygraph is a scientific aid for investigation. Such equipment will eliminate the need for any investigating agency to rely on third degree methods'', an official said.

In several earlier cases, the Crime Branch had to send suspect persons to the FSLs in Karnataka and Tamil Nadu to conduct polygraph tests. The delay in getting the test results and expenses involved had worked to the disadvantage of the Crime Branch. With the polygraph fully functional now, the test is likely to be conducted on suspects in all major cases under active investigation by the unit.

An official pointed out that the polygraph test is based on the scientific premise that lying is accompanied by specific and perceptible physiological and behavioural changes. These include signs of tension, agitation, respiratory changes, blanching, blushing and so on. The polygraph detects the "guilt consciousness'' in a suspect by assessing various parameters such as the blood pressure level, respiratory rate, pulse rate and reaction time while responding to different queries, including ``critical'' questions regarding the crime.

For instance, the skin reaction (electro-dermal activity) of the subject is monitored through stainless steel electrodes attached to the fingertips of the suspect. Pneumatic sensory belts are secured around the upper chest and abdomen of the candidate to monitor changes in respiratory pattern. An equipment known as "sphygmomanometer'' measures the relative changes in the subject's blood pressure.

The examiner conducting the polygraph test would be a specially trained police officer or a clinical psychologists. The test would commence with the examiner collecting information from the subject about his life in general and the crime in particular. The subject would be fully told of the functioning of polygraph machine before the test commences.

The subject would be asked questions from a questionnaire carefully structured by investigators. ``Crucial questions relating to the crime are sprung upon the suspect during normal questioning. The questions are structured in such a manner that the subject has to answer in monosyllabic yes or no mode. The bodily reactions are assessed for each question to understand whether there has been any deception'', an official said.

The Crime Branch is likely to rely on polygraph test results to crack what officials term as "blind cases''. The police departments of Karnataka, Tamil Nadu and agencies such as the Central Bureau of Investigation (CBI) use polygraph tests extensively. The Crime Branch is also likely to upgrade the polygraph unit now at its disposal.

Printer friendly page  
Send this article to Friends by E-Mail

Southern States

News: Front Page | National | Southern States | Other States | International | Opinion | Sport | Miscellaneous |
Advts: Classifieds | Employment | Obituary |

Stories in this Section

• Free software best option for e-governance?
• KU B.Com exam results out
• A beacon of hope for fishermen
• TSP funds tell a sordid tale
• Power sector privatisation could be disastrous: study
• Officialdom denies misuse of TSP funds
• Plus Two admissions getting delayed
• Crime Branch to rely on lie-detector tests

Copyright © 2002, The Hindu. Republication or redissemination of the contents of this screen are expressly prohibited without the written consent of The Hindu