Former RG Kar Medical College principal Sandip Ghosh sat for a polygraph — or a lie-detection — test at the CBI office in Salt Lake on Saturday but the procedure had to be stopped because of some “technical problems”, sources in the agency said.

Ghosh was asked to turn up at the office again on Sunday to undergo the test.

Four junior doctors at RG Kar, too, underwent the test one by one on Saturday.

The test was performed by officials of the Central Forensic Science Laboratory at the behest of the CBI, which is investigating the rape and murder of a junior doctor at RG Kar.

Ghosh, who resigned as RG Kar principal after the crime, and five others — the four junior doctors and Saurav Bhattacharya, a civic volunteer — had consented to undergo the test.

The CBI will also subject Sanjay Roy, the lone accused in custody, to the test. Roy, who was a civic volunteer attached to Kolkata Police, is in judicial remand and lodged at Presidency Correctional Home.

CBI officials said they have communicated to jail officials to prepare a set-up suitable for the test in the jail by Monday.

“Till now we have evidence to suggest the direct complicity of only one person in the crime. We will compare the polygraph test reports of the remaining six (Ghosh, four junior doctors and Bhattacharya) to decide our next steps,” said a CBI officer.

During the polygraph test, the person is asked a few questions to which he or she has to answer in “yes” or “no”.

The person is asked questions while his or her body parameters such as heart rate, blood pressure and other minute body responses are monitored. Usually, a wrong answer shows sudden fluctuations in the parameters, said a forensic doctor not attached to the case.

The CBI has questioned Ghosh and the other five several times in the past week.

Ghosh was quizzed at least seven times but the CBI has not got any direct evidence that could lead to his arrest for the rape and murder, sources in the agency said.

“But we would like a few confirmations through the polygraph test,” said a CBI officer.

Failing a polygraph test would not make the person liable to legal action but
law enforcement officers often use the test to assess whether the investigation is headed in the right direction.

CBI officers are quizzing police personnel who were on duty at RG Kar on August 9, the day the young doctor’s body was found, and also Kolkata Police officers who were investigating the case till Calcutta High Court handed the probe to the central agency.

Sources said all of them were repeatedly asked about the sequence of events and the procedure followed by the police after the doctor was found dead.

At least four women officers in the detective department of the city police were questioned at the CBI office in CGO Complex in Salt Lake for several hours on Saturday.

CBI sources said the agency was recording statements of the police personnel to check whether there was any mismatch in their versions. The sources said a few inconsistencies have been found.

Kolkata Police assistant sub-inspector Anup Dhar, attached to the police welfare committee, was spotted entering the CGO Complex with a file in hand on Saturday.

A few days ago, Dhar was seen running into the building after reporters questioned him about his alleged links with Sanjoy Roy, the accused.

CBI sources said the sleuths asked Dhar about the call he received from Roy on the morning of August 9.

Dhar was allegedly instrumental in getting Roy a bed in the barracks of the fourth battalion of Kolkata Police and a motorcycle. As a civic volunteer, Roy was not entitled to either, officers said.

The CBI on Saturday brought the motorcycle that Roy used to the CGO Complex. The city police had earlier seized it.