The CBI, which took over the probe from the Kolkata Police on the direction of the Calcutta High Court, has questioned Ghosh for over 74 hours in the last six days.  Sources in the CBI said that his driver has also been summoned for questioning and a thorough search of his car was carried out.

Bulbul Mukhopadhyay, who was recently appointed as the medical superintendent of the hospital after the protests over the rape-murder incident, was also summoned by the CBI.

Later in the day, Mukhopadhyay was transferred by the state Health Department on the demand made by protesting junior doctors.

Bulbul Mukhopadhyay was questioned about the management of the RG Kar Medical College and the role of the former principal, sources in the CBI said.

Dr Arunabh Dutta Chowdhury, the head of the Pulmonary Medicine Department at the hospital, was also questioned for the second day on Wednesday. The deceased junior doctor worked in his department.

The CBI is scheduled to provide an update on its investigation to the Supreme Court on Thursday.

The agency has been questioning two key individuals — Sanjay Roy, the civic volunteer who is the main accused, and Sandeep Ghosh.

The CBI has also submitted the 3D scanning of the crime scene, along with documents and video footage, to the Supreme Court. The agency has recreated the crime scene multiple times and collected samples with the assistance of experts. CCTV footage showing the movement of the accused has also been analyzed.

The CBI is exploring two potential angles involving Sandeep Ghosh. The agency is investigating whether Sanjay Roy acted alone or if there was involvement from others.

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