Calcutta High court ordered CBI inquiry following a plea made by Nasiruddin's wife Manuja Bibi in which she had alleged that Nasiruddin was killed in police custody on January 18.
Police had said he died due to excessive drinking.
CBI officers, led by a deputy superintendent of police, met Manuja Bibi and Nasiruddin's friend Sabed Ali and interrogated them for nearly an hour. They also visited Dhaniakhali police station.