The CBI has not yet been able to collate enough evidence against former RG Kar Medical College and Hospital principal Sandip Ghosh and former Tala police station officer-in-charge Abhijit Mandal to be able to file a chargesheet, officers in the agency said.

The officers, who spoke on condition of anonymity, said they had yet to collect enough evidence that could establish the charges of “destruction of evidence” and “larger conspiracy” in the rape-and-murder case that was needed to file a supplementary chargesheet against the two.

The investigation will continue, one of the officers said.

The central agency made a one-line submission before the court on Friday saying they were not filing any supplementary chargesheet “for the time being”. It did not cite any reason for the decision.

An officer in the investigation team said their main focus at the moment is on the “trial of the mother case”, which deals with the rape and murder of the postgraduate trainee doctor in a seminar hall on the third floor of the Emergency building at RG Kar Medical College and Hospital on August 9.

Ghosh was then the principal of the medical college and Mandal the officer-in-charge of the local Tala police station.

The chargesheet submitted by the CBI in the case names only one accused — Sanjay Roy — who allegedly committed the crime.

That trial, which began within three months of the rape and murder, is in an advanced stage as a large number of witnesses have deposed.

“Our main focus now is on the mother case. The trial is being held expeditiously and we expect to wrap it up soon. If we add the names of two more accused who are not directly charged with rape and murder but with destruction of evidence and larger conspiracy, it could affect the trial and would have prolonged it. We do not want to rush and jeopardise the trial,” he said.

The officer said they would continue to collate evidence against Ghosh and Mandal and submit them before the court at the “right time.”

According to the law, there is no bar on an investigating agency from filing a supplementary chargesheet at a later stage even if the accused has obtained bail.

Earlier, the CBI had claimed before multiple courts that they were investigating the roles of both Ghosh and Mandal for their alleged involvement in the “destruction of evidence” and for “larger conspiracy” in the rape-and-murder case.