The CBI has to tell a bench headed by the Chief Justice of India on Thursday what more than eight days of its investigation into the rape and murder of a young doctor at RG Kar Medical College and Hospital has thrown up.

The agency, which has been asked by the Supreme Court to submit a status report of the probe on Thursday, has not formally spoken yet on the investigation, though it has questioned at least two dozen people and spent more than 50 hours at the crime scene.

On Wednesday evening, senior officers of the central agency were piecing together the information and evidence to be submitted to the court.

The report, which is to be tabled in a sealed envelope, should mention the steps the CBI has taken since getting the case diary and the custody of the only person arrested in the case — Sanjay Roy.

Did one person or many commit the crime? That is one question whose answer has yet to be found.

Many said they were hopeful the CBI would clarify that on Thursday.

CBI sources said any conclusion could be drawn only with the support of “scientific evidence”.

“The action taken by the officers would be justified by the evidence collected. We will not speculate anything. By now the investigators have had the chance to interrogate Sanjay Roy for over a week. They also have the post-mortem report from which the nature of injuries on the victim is clear. The forensic reports, which will help us ascertain whether there were more attackers, are pending,” a CBI officer said from Delhi.

The CBI has sought permission for a polygraph test on Roy because it wants to pursue certain leads that emerged from questioning him, sources said.

The agency, the sources said, would apprise the apex court that they are pursuing leads that need confirmation through Roy’s polygraph test.

The report to be tabled in the apex court is expected to mention the “grey areas” in the case.

The CBI took over the probe more than a week ago amid allegations against Kolkata Police that they were shielding the “real culprits” and tampering with evidence.

Many thought that the central agency would make new arrests in the case. However, despite long hours of quizzing witnesses, multiple visits to the crime scene and marathon interrogation of the lone accused, the CBI has not been able to arrest any person in the case.

A senior officer in the central agency said on Wednesday: “We are sticking to the evidence and statements that are corroborated by evidence so that no action can be challenged later.”

Sources said that apart from the scientific analysis of Roy’s call details, the CBI has collected the call records of the mobile phone tower closest to the scene of crime and scanned the mobile numbers active in the area around the time the crime was committed.

CBI officers said they have questioned the majority of the witnesses whose presence
was found in and around the crime scene around the time the doctor was raped and
murdered.

The report is also likely to mention the alleged role of Sandip Ghosh, the former principal of RG Kar, who was quizzed by the CBI for the sixth consecutive day on Wednesday.

On Wednesday, the CBI summoned Ghosh’s former driver and searched the official vehicle that Ghosh used when he was the RG Kar principal.

The agency also quizzed Bulbul Mukhopadhyay, RG Kar’s new medical superintendent and vice-principal.