Turkey on Tuesday arrested the chief adviser to the leader of the main opposition Republican People’s Party (CHP) in the ongoing probe into the failed July coup attempt, media reported. Fatih Gursul, adviser to CHP chairman Kemal Kilicdaroglu, had reportedly used Bylock, an encrypted messaging application that was used by the Gulen movement, Xinhua news agency reported. Gursul was arrested at his residence here and is expected to be transferred to Istanbul for legal proceedings.