Sources with close knowledge of the investigation, who spoke to TimesLIVE on condition of anonymity, believe that her son may be able to help police.
He went missing at the same time as his mother.
The woman's cellphone was tracked to the dam where investigators found the family car abandoned.
Police spokesperson Thulani Zwane said that detectives had concluded that Durugan was murdered.
“She was reported missing together with her son, Sagren Pillay, and police have intensified their search of the 46-year-old son,” he said.
“Anyone who can assist police is urged to contact warrant officer Cleo Loganathan at Saps Chatsworth on 0798374182. Alternatively, call Crime Stop on 08600 10111.”