The CBI has said that it has no idea who recorded conversations between its prosecutor in the telecom scam and Unitech Managing Director Sanjay Chandra, one of the main people being investigated by the agency. The CBI fired the prosecutor, AK Singh, who is allegedly heard offering legal advice to Mr Chandra. Today, the agency's chief, Ranjit Sinha, told a parliamentary committee that's studying the scam that the CD was delivered anonymously ten days ago to a senior official, and that its authenticity is being verified through forensic tests.