Miss. Code § 19-25-15
Motor vehicles purchased or leased by the county for the sheriff's office shall be clearly marked on both sides with the words "SHERIFF'S DEPARTMENT." The use of large auto door decals shall constitute compliance with this section. Each such motor vehicle shall be marked on the sides or trunk top with the name of the county in clear letters of no less than four (4) inches in height. However, in instances where such identifying marks will hinder official investigations, the board of supervisors may authorize the sheriff's department to use a specified number of unmarked vehicles. The approval of the board shall be entered on its minutes and shall contain the manufacturer's serial number and the reason why the vehicle or vehicles should be exempt from provisions of this section. In addition, the manufacturer's serial number of all county-owned sheriff's department vehicles not subject to the exemption shall be included in such resolution or order of approval, and a certified copy thereof shall be furnished the State Department of Audit. Any vehicle found to be in violation of this paragraph shall be reported immediately to the sheriff and the board of supervisors, and fifteen (15) days shall be given for compliance; and if not complied with, such vehicles shall be impounded by the State Auditor until properly marked or exempted.
Miss. Code § 19-25-15