The CBI will soon initiate a formal probe into the doping scandal allegedly involving wrestler Narsingh Yadav. <br/><br/>CBI sources said in New Delhi that it has started examining the complaint and the material received from the Prime Minister's Office in this regard.<br/><br/>The sources said they are examining the material which has been submitted with the complaint filed by the Wrestling Federation of India (WFI).<br/><br/>Yadav was slapped with a four-year ban last month by the Court of Arbitration (CAS) during the Olympics barring him from the Games. After the development, the WFI had been demanding a CBI probe into the matter.