Kolkata doctor murder case: What is a polygraph test?

Kolkata doctor murder case: Polygraph test of seven people, including Sanjay Roy and former principal Sandip Ghosh, accused in the rape and murder case of a trainee doctor at Kolkata's RG Kar Medical Hospital, is being conducted at the agency's Kolkata office.

Kolkata doctor murder case: What is a polygraph test?

Kolkata Doctor Murder Case CBI is making new revelations every day in the case of rape and murder of a trainee doctor at Kolkata's RG Kar Medical College and Hospital. Apart from the arrested civic volunteer Sanjay Roy, no other accused is mentioned in the CBI's remand note. Former principal of RG Kar College Dr. Sandeep Ghosh is also under investigation in the case. In this connection, CBI is conducting polygraph test of seven people today. Polygraph test of accused Sanjay Roy, former principal Sandeep Ghosh, the doctor present with the victim at the time of the incident and a volunteer is being conducted at the agency's Kolkata office.

Why is a polygraph test being conducted?

The evidences that the CBI has received so far have not been able to confirm the incident. The CBI now wants to know whether the statements given by the medical college staff are true or whether the evidences have been tampered with.

What is a polygraph test?-

A lie is caught through a polygraph test and it is done with the consent of the court. In this, the criminal is exposed through a lie detector machine. The changes in the body of the accused while answering reveal whether he is speaking the truth or a lie. Although the polygraph test is not considered a very effective evidence, the court cannot ignore it completely.

This machine has many parts. Its units are connected to the body parts of the accused and then when the accused answers, data is received. All this data goes to a main machine and there the truth and lie are detected. These units of the machine are installed on the head, mouth and fingers. In this, pulse rate and breathing rate are measured, which helps in detecting lies and truth.

First of all, general questions are asked to the accused, which have nothing to do with the case. After this, the accused is asked questions in yes or no format, which reveals the truth of the machine's data. In this, results are drawn according to the data of pulse rate, blood pressure, physical sensations, breathing, and changes on the skin. In the test, different signals come out from the brain of the accused who lies. P300 (P3) signal comes out from the brain of the accused and his heart rate and blood pressure increase.