Central Bureau of Investigation (CBI) filed a chargesheet on Thursday against Bishal Phukan, Abhijit Chanda, Sumi Bora, and Tapon alias Tarkik Bora in the ‘Dibrugarh Investment Scam Case’ before the Special CBI Court in Guwahati. This marks a significant development in the investigation into the large-scale financial fraud, completed within 90 days of the arrests.