The CBI filed a supplementary charge sheet against Deepankar Barman, the mastermind of a Rs 400 crore Ponzi scam in Assam. His company, DB Stock Consultancy, allegedly duped investors with unregulated schemes promising high returns. Arrested in October, Barman and other accused, including Monalisha Das and Chabin Barman, are facing trial. The CBI has filed charges in 20 out of 41 related cases.