S.D. Codified Laws § 26-9-4

Probation officers having the powers of peace officers, as well as state's attorneys, shall have the right and be vested with all power necessary to file complaints against any person under § 26-9-1 and to prosecute any such case. In all such cases it shall be the duty of the state's attorney to prepare any such complaints and prosecute any such cases for such probation officer when so requested by such officer or the judge of the circuit court; but nothing herein shall be construed to interfere with any state's attorney prosecuting such cases under this or any other law as in other criminal cases.