Okla. Stat. tit. 19, § 215.37G

Purchases made from district attorney appropriations shall be made in accordance with the procedures prescribed by statute for county officers, departments and agencies except that neither the purchases nor the expenditures for such purchases shall be subjected to the approval of the board of county commissioners. It shall be the mandatory duty for the designated county officials to issue, sign, attest, register and pay the warrants required to pay such obligations.