MUMBAI: Nearly a month after the Bombay High Court transferred to CBI the probe into the murder of anti-superstition activist Narendra Dabohalkar in Pune last year, the central agency today registered an FIR against unknown persons."We have registered an FIR in the Dabholkar murder case under section 120b (criminal conspiracy) and 302 (murder) against unknown persons," a CBI spokesperson said.The case was registered on transfer from Pune police as per the High Court order.The Bombay High Court had transferred the probe to CBI on May 9 on a PIL filed by former journalist Ketan Tirodkar on the plea that there was no headway several months after the killing of the eminent rationalist.Dabholkar was shot dead by unknown assailants in Pune on August 20, 2013.The CBI was initially reluctant to take up the case with its counsel contending that no allegations had been levelled against the state or its police of conducting shoddy investigation.Tirodkar had pleaded that even if no allegations had been made against state authorities, the probe in a criminal case could be transferred to CBI if it has national or international ramifications.Pune police had earlier submitted case diaries and confidential reports to the court. After going through them, the judges had sought to know the status of the probe, and asked CBI what its stand was.The government had also informed that so far the main conspirators had not been arrested, and those who were, had got bail.Dabholkar's daughter Mukta, who has been allowed to intervene, had said the family wanted the HC to monitor the probe. She had earlier demanded formation of a Special Investigating Team as local police had failed to make any progress.