CBI sleuths on Saturday started questioning another doctor, allegedly close to arrested former principal of RG Kar Medical College and Hospital Sandip Ghosh, in connection with their probe into the rape and murder of a woman doctor at the medical establishment, an officer of the agency said.

Birupaksha Biswas, who was recently transferred by the West Bengal Health Department from Burdwan Medical College and Hospital to remote Kakdwip hospital in South 24 Parganas district, appeared before officers of the Central Bureau of Investigation (CBI) at its CGO Complex office in Salt Lake area.

Biswas, allegedly part of a 'North Bengal lobby' operational in medical colleges, was seen at RG Kar Hospital on August 9, when the body of the woman medic was found, the CBI officer said.

The 'North Bengal lobby' is being referred by medics in West Bengal to a group of doctors and officials posted at state-run medical establishments who allegedly threatened students.

"He is being questioned about his presence at RG Kar Hospital on August 9 despite having no official engagement, apart from other queries," the officer told PTI.

Incidentally, an FIR has been lodged against Biswas and two other doctors -- Avik De and Ranjit Saha – with Bowbazar police station for allegedly threatening students at different medical colleges and hospitals across West Bengal.

They have been booked under Section 351 (assault as making a gesture or preparation causing someone to believe that they are about to be subjected to criminal force) of Bharatiya Nyay Sanhita.

Except for the headline, this story has not been edited by The Telegraph Online staff and has been published from a syndicated feed.