Polygraph test conducted on 1,314 suspects so far

Kathmandu, January 5

Nepal Police has conducted polygraph tests on as many as 1,314 suspects in course of crime investigation throughout the country since the technology was first introduced on February 6, 2014.

According to statistics maintained by the Crime Investigation Department, at least 225 suspects underwent lie detector test in the fiscal 2013/14, 467 in 2014/15 and 333 in 2015/16. Similarly, crime investigators carried out the test on 218 suspects during the first five months of the current fiscal.

During interrogation, 600 suspects spoke the truth while 638 others made a false statement to the police. In rest of the cases, the statements given by suspects were deemed neutral. Polygraph test was also used for the purpose of investigating alleged involvement of police personnel in bribery, irregularity and unethical conduct.

Murder suspects topped the figure of the polygraph test with 541 followed by theft cases (191). It was also massively used during investigation of cases related to road accidents, arms and ammunition, corruption, rapes, fraud and kidnapping, read a report of the CID.

Five persons, including lawmaker Lharkyal Lama, refused to undergo polygraph test in connection with bullets recovered from his bank locker. A senior police official said the test was not obligatory for a crime suspect.

The law enforcement agency has 12 polygraph kits and 10 examiners certified by the American Polygraph Association. The Metropolitan Police Office, Central Investigation Bureau, Special Bureau, Narcotics Control Bureau and Eastern Regional Police Office, Biratnagar are currently using lie detectors.

However, the Central Polygraph Section at the CID also deputes examiners with necessary kits to any police unit on demand.

Polygraph is being used for criminal and internal investigation guided by Nepal Police Polygraph Directive, 2014. Polygraph examinations are scientifically accepted as a tool in crime investigations.

Polygraph system is also called ‘psycho-physiological detection of deception’ and it is one of the techniques of credibility assessment. Polygraph technique has been found to be effective in making suspects speak the truth during crime investigation.

The machine records changes in physiological characteristics, such as respiration, heartbeat and blood pressure. Four to six sensors are attached to a person during a polygraph test.

The sensors usually record the person’s breathing rate, pulse, blood pressure, perspiration and sometimes arm and leg movement.

A significant change in behaviour such as faster heart rate, higher blood pressure and increased perspiration indicate that the person is lying.

However, these test reports cannot be produced in court as evidence.