Western Cape detectives are following leads to find the people who killed the elderly parents of education expert Professor Graeme Bloch in their home, provincial police said on Sunday.
No arrests had yet been made and there were "no new developments to report at this stage", said Sergeant Noloyiso Rwexana.
Rosalie Bloch, 84 and Aubrey Jackson, 94, were found tied up and murdered in their Victorian double-storey home in the quiet suburb of Rosebank, Cape Town, on Saturday.
Their bodies were discovered at about 09:00 on Saturday by a relative who went to fetch them, police said previously.
Cases of murder and house robbery were opened.
It was not immediately clear what was taken from the house.
Detectives were looking at CCTV footage from a nearby guesthouse to find leads, Netwerk24 reported.
A police source reportedly revealed that two black men and a white woman were identified as possible suspects on the footage.
On Saturday, the ANC expressed its shock and sadness at the "brutal, callous and cold-blooded killing" of Bloch's parents. Bloch is married to former politician Cheryl Carolus.
"We strongly condemn the cowardly act visited on the defenceless and elderly. It is disheartening to note that we still have amongst us, those who are determined to trample on other people's right to live driven by selfish and cruel intentions," ANC spokesperson Pule Mabe said in a statement.
He urged law enforcement agencies to work hard in their quest to ensure that the couple's murderers were caught and that they face the full might of the law.
Mabe called on all South Africans to act in concert to ensure that criminals had nowhere to hide.
The South African National Civic Organisation (SANCO) also expressed its shock at the murders.
SANCO spokesperson Jabu Mahlangu said much more still needed to be done to protect the aged against violent crime.