Kolkata, Sep 13 (IANS): A lower court in Kolkata, on Friday, rejected the Central Bureau of Investigation’s (CBI) plea to conduct a narco-analysis test of civic volunteer Sanjay Roy, the sole accused in the ghastly rape and murder of the junior doctor at the state-run R.G. Kar Medical College & Hospital in the city last month.

The court rejected CBI’s appeal since the accused refused to give the necessary consent for the test to be conducted on him. As per protocol, the court can only give permission to any investigative agency to conduct a narco-analysis or polygraph test on any person, provided the person concerned gives consent for the same.

A polygraph test has already been conducted on Roy since he gave the consent for the same.

There is a basic difference between polygraph test and narco-analysis. A polygraph test also popularly known as a ‘lie detector’ test measures physiological responses like blood pressure, pulse, and respiration of the person who is being questioned based on the idea that physiological responses of a person are different when they are lying.

On the other hand, narco-analysis involves injecting the person to be questioned with sodium pentothal, popularly termed ‘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.

Sources said that the CBI officials wanted the narco-analysis test to be done on Roy to match his answers there with those he gave during the polygraph test. Now with permission for the same not available from the court, sources said, CBI is currently working out an alternative strategy to carry forward the investigation in the matter.

On Wednesday, the CBI officials also collected the teeth-impression of Roy. Sources said that the teeth impression of the accused is often considered important evidence in case of any investigation in rape or rape & murder cases and since Roy is the sole arrested accused in the case so far, the same for him has been collected by the CBI.