The CBI has finally taken over the investigation in one of the most high profile cases of 2020 - the death of Bollywood actor Sushant Singh Rajput - that involves several political controversies between the Maharashtra and Bihar governments and both states police forces.The Central Bureau of Investigation (CBI) decided to get the case probed by the Anti Corruption Unit VI (SIT) New Delhi, which had earlier probed the Rs 3,600 crore AgustaWestland VVIP chopper deal and liquor baron Vijay Mallya's loan fraud case.According to CBI sources, the agency handed over the probe to the ACU-VI (Special Investigation Team), which was formed by CBI's Special Director Rakesh Asthana. The decision was taken after hours of brainstorming among the top CBI officials including Director R.K. Shukla.After the brainstorming session of top officials, the case was handed over to the ACU-VI (SIT). The CBI on Thursday evening registered a case into the death of Sushant on the recommendation of the Bihar government and named Sushant's girlfriend Rhea Chakraborty, her father Indrajit Chakraborty, her mother Sandhya Chakraborty, her brother Showik Chakraborty, Shruti Modi, house manager Samuel Miranda and unknown others in the case.Sushant was found dead in his flat in Mumbai's Bandra on June 14. On Tuesday, Bihar Chief Minister Nitish Kumar recommended a CBI probe on the request of Sushant's father K.K. Singh. Many political leaders have also called for a CBI probe into Sushant's death.On K.K. Singh's complaint, the Bihar Police registered a case against Rhea on July 25. Sushant's father had lodged an FIR against Rhea in Patna, accusing her of cheating and threatening his son. Sushant's family has also accused her of keeping him away from them. K.K. Singh in his complaint also alleged that Rs 15 crore was transferred from the Kotak Mahindra Bank account of the late actor, which earlier had Rs 17 crore.The SIT team consists of Joint Director Manoj Shashidhar, a 1994-batch Gujarat cadre IPS officer, DIG Gagandeep Gambhir, also a Gujarat cadre IPS officer, and Superintendent of Police Nupur Prasad.Gambhir, was born and brought up in Bihar's Muzaffarpur. She completed her higher education from Punjab University. According to CBI sources, Gambhir had last year also probed the role of former Uttar Pradesh Chief Minister and Samajwadi Party chief Akhilesh Yadav in the alleged illegal sand mining case. Later she was shifted to the unit probing the Srijan scam and the case of journalist Upendra Rai. The SIT has also successfully probed the Vijay Mallya case.The source said, due to the tight probe the CBI was able to win the extradition case against the former chairman of the now defunct Kingfisher Airlines. The SIT has also probed the Rs 3,600 crore AgustaWestland VVIP chopper deal, in which it has arrested British national and key middleman Christian Michel James, who was extradited to India in December 2018.At the time of filing this report, the Enforcement Directorate (ED), which also registered a money laundering probe into the death of Sushant, is questioning Rhea at its Mumbai office. Rhea is at the ED office in Mumbai along with her brother Showik, who is also named in the CBI and ED cases. The ED had earlier questioned Samuel Miranda, Sandeep Sridhar, the chartered accountant of Sushant, and Ritesh Shah, the CA of Rhea.