This is the fourth consecutive day that Ghosh has appeared for interrogation at the central agency office. He faced marathon questioning for 13 to 14 hours each day since last Friday.

Ghosh refrained from answering the questions of the media persons each time he exited from the CBI office during the early hours. At the same time, the CBI officials have remained tight-lipped on why Ghosh is being summoned multiple times.

The mobile phone Ghosh has also been sent for forensic examination to track whether any data like call lists or messages exchanged have been deleted from the records of the phone or not, the source added.

Meanwhile, sources said that the investigating CBI officials are trying to figure out whether the seminar hall at the hospital building, where the body of the victim was recovered on the morning of August 9, was really the “scene of the crime” or the actual crime was committed elsewhere and then the body was placed there.

To be sure of that, sources said that the CBI officials are conducting 3D mapping of not just the seminar hall but different pockets of the hospital, especially the chest medicine department, where the victim doctor was attached.

The central agency officials at the same time are questioning different individuals attached to the hospital to have a clear idea in the matter.

The CBI officials are also trying to figure out whether the attempted renovation at a room adjacent to the seminar hall by PWD staff on the evening of August 13, just a few hours after a division bench of Calcutta High Court ordered a CBI probe in the matter, was done as per instructions of Ghosh.