The CBI on Tuesday registered a preliminary inquiry against former Gujarat ministers in the Ishrat Jahan encounter case.br br The CBI has recovered a CD showing the ministers discussing how to derail the casebr The conversations on the CD date back to November 2011 and take place a day before a SIT appointed by the Gujarat high court was to submit its report in the case.br br The CD has 70 minutes of audio and the CBI could summon all concerned for questioning.