A witness has a privilege to refuse to disclose the identity of a person who has furnished information purporting to disclose a violation of a provision of the laws of this state or of the United States to a representative of the state or the United States or a governmental division thereof, charged with the duty of enforcing that provision, or to a member of a crime stoppers chapter recognized by the Kansas state crime stoppers organization, and evidence thereof is inadmissible, unless the judge finds that: (a) the identity of the person furnishing the information has already been otherwise disclosed; or (b) disclosure of such person’s identity is essential to assure a fair determination of the issues. The privilege extends to documenting records as well as testimony.