"This is a routine transfer and a part of the transfer policy," a CBI spokesman said.
The CBI on Thursday said it has transferred from the city four officers, three of them deputy superintendents of police and one inspector, who were involved in the investigations into the Saradha and Rose Valley ponzi scams and Narada tapes scandal, from the city.
Those transferred are CBI deputy superintendent of police Ranjit Kumar, who was probing the Narada tapes scandal, DSP Tathagata Bardhan, involved in the Saradha ponzi scam probe and DSP Chojom Sherpa investigating the Rose Valley chit fund scam, a CBI spokesman said.
The fourth CBI officer to be transferred is Inspector Bratin Ghoshal, a former investigation officer probing the Rose Valley chit fund scam, sources said.
While Ranjit Kumar and Tathagata Bardhan were transferred to New Delhi, Chojom Sherpa was posted to Bhubaneshwar.
"This is a routine transfer and a part of the transfer policy," a CBI spokesman said.
One of the officers said, "This is a mass transfer. I do not know whether this is routine or not".
The central agency started the probe into the Saradha chit fund case in May, 2014, and the Rose Valley ponzi scam case at around the same time.
The investigation into the Narada sting, which showed persons resembling senior Trinamool Congress leaders and a police officer accepting money from representatives of a fictitious company in return for favours, began in March, 2017.
Earlier this month, the central investigating agency shifted Deputy Inspector General Abhay Singh to the Economic Offences Wing in Delhi from the Special Crime Branch in Kolkata.
Superintendent of Police Partha Mukherjee whose unit Economic Offences IV, based in Kolkata, was probing chit fund cases, had been transferred to the headquarters as additional inspector general (policy) in New Delhi.