A Darlington County grand jury indicted April Dixon, 23, and Timothy Sanders, 40, on charges of Murder and Conspiracy in the death of their daughter 21-month-old Madison Dolford.
The grand jury found the evidence against the couple was enough that the case could proceed to trial.
Prosecutors are waiting on DNA results to determine if Sanders is the child's father. They say Dolford's paternity is needed because it may further establish a motive.
Sanders and Dixon are expected to undergo mental evaluations. Prosecutors aren't saying why the evaluations are relevant to the investigation.