Renegade is used to describe a member of a group or profession who behaves in a way that is opposed to the normal behaviour or beliefs of that group or profession. Three men were shot dead by a renegade policeman. someone who leaves one side in a war, politics etc in order to join the opposing side - used to show disapproval (renegado, from renegare , from negare; NEGATE)
A renegade is a person who abandons the religious, political, or philosophical beliefs that he or she used to have, and accepts opposing or different beliefs
[ 're-ni-"gAd ] (noun.) 1583. Spanish renegado, from Medieval Latin renegatus, from past participle of renegare to deny, from Latin re- + negare to deny; more at NEGATE.