Tex. Code Crim. Proc. art. 24.17

The officer receiving said subpoena shall execute the same by delivering a copy thereof to each witness therein named. He shall make due return of said subpoena, showing therein the time and manner of executing the same, and if not executed, such return shall show why not executed, the diligence used to find said witness, and such information as the officer has as to the whereabouts of said witness.