Former IPS officer from West Bengal, Bharati Ghosh, on Monday joined the BJP here and termed Chief Minister Mamata Banerjee's 'dharna' a political move to stop the CBI investigation into the ponzi scheme scams. Ghosh, once a favourite of Banerjee, reportedly fell from grace and sought voluntary retirement after she was transferred as Commandant of the West Bengal Armed Police's 3rd Battalion. Her application was accepted in January 2018.