The Central Bureau of Investigation (CBI) on Thursday said it was in the process of filing a case in the death of Sushant Singh Rajput after the probe by the Bihar Police, based on a complaint filed by the actor's father, was transferred to the agency.Sushant Singh Rajput, a rising star in Hindi films, was found dead in his Mumbai apartment on June 14. The Mumbai Police said it was suicide and has questioned over 50 people on allegations that the actor was suffering from depression and had felt sidelined because of cut-throat rivalries in the film industry.