A police officer said Chaitali Das Sharma was arrested following a tip-off from Tinkonia bus stand area of the town.
She was later remanded to jail custody till January 24.
Das Sharma, who was from Kolkata, was the alleged accomplice of one Gourab Bhattacharjee who had been arrested previously for impersonating as a CBI officer.
Both were being separately interrogated to bust the racket which allegedly raise money from people by issuing false threats.