Lachara Bordeaux, 26, pleaded guilty to helping Jared Stone elude authorities in April.
Stone is facing murder charges in the shooting death of Baptiste White Eyes outside the Lucky Lady Casino in Sioux Falls.
Authorities say Bordeaux helped stone hide from police in Sioux Falls.
She was later arrested in Le Mars, Iowa, where she told authorities Stone held her at gunpoint.
Bordeaux is scheduled to be sentenced in November.
Two other women, Mercedes Red Bear and Desiree Sully, also pleaded guilty to being accessories.