S.D. Codified Laws § 12-18-10
If a person makes an application for ballots, or if an absentee ballot has been cast, the person's right to vote at that poll and election may be challenged only as to the person's identity as the person registered whom the person claims to be or on grounds that within fifteen days preceding the election the person has been convicted of a felony or declared by proper authority to be mentally incompetent. The proceedings shall be conducted before the precinct superintendent and precinct deputies who shall determine from the evidence presented whether or not the person is permitted to vote and the members of the precinct election board shall indicate beside the name on the registration list the ground stated and the result of the precinct election board's decision.
SDCL 12-18-10