A 20-hour interrogation by the Enforcement Directorate (ED) culminated in the arrest of Bengal cabinet minister and TMC secretary general Partha Chatterjee at 2.10am on Saturday and his alleged “close associate” Arpita Mukherjee later in the day, capping a run of events starting with Friday’s swoop on the latter’s south Kolkata apartment that yielded a cash stash of Rs 21.9 crore.A 20-hour interrogation by the Enforcement Directorate (ED) culminated in the arrest of Bengal cabinet minister and TMC secretary general Partha Chatterjee at 2.10am on Saturday and his alleged “close associate” Arpita Mukherjee later in the day, capping a run of events starting with Friday’s swoop on the latter’s south Kolkata apartment that yielded a cash stash of Rs 21.9 crore.