The mother of the murdered baby had phoned Margrietha de Goede, the caregiver, a few times to check on her child who was sick, but there was no answer.
The woman and a friend then went to the day mother's house, but became concerned when they heard a child crying.
They broke a window to gain entry to the house where they found an 18-month child, and called police when De Goede and the other baby, Wiehan Botes, could not be found.
Police arrived and made the grisly discovery of the Wiehan's body under a bed, a police spokesperson said.
De Goede, in her 60's, was later found dead in a garden shed.
Police forensics officials were on the scene until after 18:00.