Tex. Rev. Civ. Stat. art. 5202

Upon the application of the Attorney General, or of any district or county attorney, made to any justice of the peace in this State, and stating that he has reason to believe that a witness, who is to be found in the county of which such justice is an officer, knows of a violation of any provision of this chapter, the justice to whom such application is made shall have summoned and examined such witness in relation to such violations.