RG Kar tragedy: CBI seeks polygraph test of former SHO, narco-analysis of ex-Principal Ghosh

Kolkata: The CBI has applied to a special court in Kolkata for permission to conduct a polygraph test on Tala Police Station's former SHO Abhijit Mondal and a narco-analysis test of former controversial Principal of R.G. Kar Medical College & Hospital Sandip Ghosh in connection with its investigation into the ghastly rape and murder of a junior doctor within the hospital premises last month.

The Central Bureau of Investigation (CBI) has already conducted polygraph tests on Ghosh and the sole arrested accused in the case, civic volunteer Sanjay Roy.

Sources said that the CBI officials want the narco-analysis test to be done on Ghosh to match his answers with those he gave during the polygraph test.

There is a basic difference between a polygraph test and narco-analysis. The polygraph test, also popularly known as lie-detector tests, measures physiological responses like blood pressure, pulse, and respiration of the person who is being questioned, based on the idea that physiological responses of persons are different when they are lying. On the other hand, narco-analysis involves injecting the person to be questioned with sodium pentothal, popularly termed the "truth drug" or "truth serum", which puts the person concerned in a stage of hypnosis which is believed to make that person speak only the truth.

On September 13, the special court rejected the CBI’s plea for the narco-analysis of Roy as he refused his consent. Neither a polygraph test nor a narco-analysis can be conducted without the consent of the person on which the test will be conducted.

Although Roy gave his consent for the polygraph test, he refused it for narco-analysis. The findings of the polygraph test or narco-analysis can be used as evidence against anyone in the court. Such tests are considered as attempts by the investigation agencies to get nearer to the truth in their probe.

Both Ghosh and Mondal are currently in the custody of the CBI, following an investigation against them about misleading the initial investigation carried out by Kolkata Police in the case as well as for making attempts to tamper with the evidence.

While the CBI arrested Mondal late on Saturday after seven hours of questioning, Ghosh, who was earlier arrested by the agency in the case of financial irregularities at the institution and was in judicial custody, was also shown as "arrested" in the rape and murder case the same day.

The West Bengal Medical Council has cancelled the medical registration of Ghosh, while Mondal has been suspended by the Kolkata Police.