Art. 16.21. DUTY OF SHERIFF AS TO PRISONERS.  Every sheriff shall keep safely a person committed to his custody.  He shall use no cruel or unusual means to secure this end, but shall adopt all necessary measures to prevent the escape of a prisoner.  He may summon a guard of sufficient number, in case it becomes necessary to prevent an escape from jail, or the rescue of a prisoner.
Acts 1965, 59th Leg., vol. 2, p. 317, ch. 722.