The CBI on Thursday conducted searches at the premises of Mayaram after filing an FIR against him and a UK-based company for alleged corruption in the supply of exclusive colour shift security thread for Indian bank notes, officials said. The CBI, in its FIR, alleged that Mayaram, the UK-based company De La Rue International Ltd and unidentified officials of the finance ministry and RBI hatched a criminal conspiracy to extend undue favour to the firm.