Central Bureau of Investigation, CBI is interrogating three doctors at CGO Complex in Kolkata in relation to the RG Kar incident. Dr Birupaksha Biswas of Bardhaman Medical College, Dr Avik De of SSKM Medical College of Kolkata and Dr Saurav Paul of RG Kar Medical College are being interrogated. All the doctors are believed to be closed to the arrested former principal Sandip Ghosh of the R G Kar Medical College.