Neeraj Agarwal, posted as DSP in the Mumbai unit of the agency, has been charged with criminal conspiracy and bribery, the FIR alleged.
It said Agarwal was probing a case against Pradip Shah, retired cashier of Bank of Baroda's Mumbai branch, but did not elaborate. Agarwal allegedly demanded bribe from Shah to help him in the matter.
The CBI officer was awarded with President's Police Medal for Meritorious Service last year.
It is alleged that Agarwal called Shah to his office where Tiwari was also present. Agarwal introduced Tiwari as an Income Tax official. Tiwari allegedly took Shah to a nearby room where he asked for a bribe of Rs 50 lakh.
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"The enquiries prima facie reveal he is neither an Income Tax official nor he is attached to CBI, Mumbai in any capacity and therefore his identity is yet to be fully established," the report said.
The FIR alleged that when Shah expressed his inability to give the amount, Agarwal called him to his cabin and coerced him to give in writing that he would submit requisite documents, though he had already submitted them.
Shah told the CBI in his complaint that he had recorded conversations with Tiwari and Agarwal on his mobile phone using automatic call recorder which he could produce before the CBI.
The probe officers heard those conversations and found them to be in "conformity" with the narration of events by Shah.
"The conversation revealed that Shah informed Tiwari that he could arrange Rs four lakh and sought an assurance from Agarwal that there would be no problem from him to which Tiwari replied in affirmative," the FIR alleged.
Tiwari has also been booked for criminal conspiracy and bribery.