(a) When the unit has credible information that indicates a person has engaged in an act or activity which is subject to prosecution under this article, the unit may make an investigation to determine if the act has been committed and, to the extent necessary for such purpose, the Attorney General, or an employee of the unit designated by the Attorney General, may administer oaths or affirmations and issue subpoenas for witnesses and documents relevant to the investigation, including information concerning the existence, description, nature, custody, condition, and location of any book, record, documents, or other tangible thing and the identity and location of persons having knowledge of relevant facts or any matter reasonably calculated to lead to the discovery of admissible evidence. When the unit has probable cause to believe that a person has engaged in an act or activity which is subject to prosecution under this article, or §61-2-29 of this code, either before, during, or after an investigation pursuant to this section, the Attorney General, or an employee of the unit designated by the Attorney General, may request search warrants and present and swear or affirm criminal complaints.