Okla. Stat. tit. 19, § 138.6

Pursuant to the provisions of this act, the county indigent defender may authorize the employment of one or more secretaries and one or more investigators and shall determine and fix the salary to be paid; provided, that such salaries shall be commensurate with the range of salaries paid by the district attorneys' offices in their districts, payable monthly, from the court fund of such county.