Okla. Stat. tit. 19, § 123

It is hereby made unlawful and deemed a Class D3 felony offense for any of the funds of the county to be deposited in any bank in which the county treasurer or any member of the board of county commissioners is the owner of any stock or otherwise directly or indirectly pecuniarily interested. A county treasurer or county commissioner shall be considered to be interested in such bank if any member of his immediate family owns any interest in said depository bank. Any person who violates the provisions of this section shall, upon conviction, be guilty of a Class D3 felony offense and shall be punished by imprisonment as provided for in subsections B through F of Section 20P of Title 21 of the Oklahoma Statutes.