Polygraph test on Kolkata horror accused Sanjay Roy, ex-principal of RG Kar Medical College begins

Chandigarh, August 24

Polygraph test on the main accused in the Kolkata murder and rape case, Sanjay Roy and 6 others, including ex-principal of RG Kar Medical College has started.

The polygraph test on the main accused, Sanjay Roy, will be conducted in the prison, where he is lodged, while the remaining six, including former principal Sandip Ghosh and four doctors who were on duty during the night of the incident and a civil volunteer, will undergo test at the agency's office, officials said.

A team of polygraph specialists from the Central Forensic Science Laboratory (CFSL) in Delhi have flown to Kolkata to conduct these tests, they said.

A special court in Kolkata on Friday had given a go ahead to the CBI to conduct the test.

Roy is the main accused in the brutal rape and murder of a junior doctor at the RG Kar Medical College and Hospital earlier this month.

On Thursday, the same court had approved the Central Bureau of Investigation's (CBI) plea seeking to conduct the test on the controversial former principal of R.G. Kar Medical College and Hospital, Sandip Ghosh, and five others in connection with the case.

What is a polygraph test?

Polygraph is a device or procedure that is used to measure and record several physiological factors of a person accused of crime. The test was first used by Italian criminologist Cesare Lombroso in the 19th Century.

When subjected to the test, an accused is asked questions, based on which his or her blood pressure, pulse, respiration, and skin conductivity are monitored as these which can vary when a person gives deceptive answers.

These are monitored via cardio cuffs or sensitive electrodes that are attached to the accused to monitor blood pressure, pulse, and other variables.

The procedure for getting court permission for a polygraph test is not simple. The court gives its nod in such cases only after the persons on whom the test will be conducted give their consent for the same.

Also, it is primarily a method adopted by investigating agencies to reach the truth, and its findings cannot be presented as evidence in the court of law.

How it is done?

Before the actual polygraph begins, the accused undergoes a series of tests. It typically begins with a pre-test round where the person is asked questions by the investigating agencies that can be used as a control.

In the second round, the accused is asked to lie deliberately to further boost the accuracy of the procedure. Known as the 'stim test', it can also make the accused nervous and anxious.

The test is considered passed if the physiological responses to the diagnostic questions are larger than those during the relevant questions.

What does the Indian law say about polygraphs?

Article 20 (3) of the Indian Constitution protects against self incrimination and gives the accused the freedom to choose for the test or to reject it.

No accused can be compelled to undergo the test. Importantly, forcing an accused to undergo the test is considered a violation of Article 20 (3).

How accurate is a polygraph test?

While a polygraph test can measure arousal, causer by anxiety, post-traumatic stress disorder (PTSD), nervousness, fear, confusion, hypoglycemia, psychosis, depression, or other factors, it cannot measure lies accurately.

These are not scientifically proven to be 100 per cent accurate.

With inputs from agencies