The CBI on Wednesday registered the 13th First Information Report (FIR) in its ongoing investigation into the Vyapam scam in Madhya Pradesh.The FIR was registered against 52 people related to allegations of altering the Optical Mark Recognition (OMR) sheets by employees of Vyapam vis-a-vis the Transport Constable Recruitment Test of 2012.The Central Bureau of Investigation has taken over the investigation of the scandal from the Special Task Force (STF) of the Madhya Pradesh Police.The CBI had earlier registered 12 FIRs and launched five preliminary enquiries into the scan involving the Vyavsayik Pariksha Mandal or Vyapam.The Supreme Court on July 9 ordered the handing over of the Vyapam cases to the central agency.More than 40 people linked to the scam have died - mostly unnaturally or under mysterious circumstances.