“We have registered a case of murder, but initially it was an inquest,” Captain Tsekiso Mofokeng said.
On Sunday morning, Diepsloot residents found the baby dead in a shack.
Police arrived to find the baby’s body with a foot missing from the body.
“Further investigations informed police that [the foot] was bitten off by rats,” he said.
Police were still awaiting the results of the post-mortem to definitively determine the cause of death.
He said the baby’s mother was missing and had still not been located by Monday morning, contrary to media reports that the mother had reported the matter to police.
Mofokeng said a case of murder was opened because part of the investigation would deal with how the baby came to be left alone in the shack.
In September a case of child neglect was registered against the baby’s mother, which resulted in her two children being placed in the care of their grandmother, he said.
The mother had picked up only the seven-month-old boy from the grandmother on Saturday.