Magistrate Desmond Nair confirmed on Tuesday that the woman, whose body was found at her home Sunday evening along with those of her sons, is a first cousin.
The woman's brother, Vishal Maharaj, identified her as Anusha Maharaj.
Nair presided over dramatic bail hearings for Pistorius last week in a case followed closely around the world. The double-amputee Olympian is charged with premeditated murder in the shooting death of his girlfriend, Reeva Steenkamp, on Feb. 14.