Odisha Chief Minister Naveen Patnaik's close aide and former IAS officer V Karthikeyan Pandian on Monday formally joined the ruling Biju Janata Dal. Mr Pandian joined the regional party in the presence of the chief minister, state ministers, lawmakers and senior BJD leaders. The 2000-batch IAS officer, who sparked several controversies and was accused of violating the service rule, had taken voluntary retirement from government service on October 23 this year.