The National Prosecuting Authority (NPA) does not intend to pursue charges against two Security Branch police officers, Seth Sons and Neville Els, who are implicated in the murder of Ahmed Timol.
In a statement, his nephew, Imtiaz Ahmed Cajee, slammed the decision as deplorable and one that would "inevitably deepen impunity for apartheid crimes in South Africa".
"Families of victims will not rest until such time as we see the NPA and the South African state live up to its international and domestic obligations.
"Many other families believe that the NPA lacks the political will to pursue these cases and would rather delay making decisions in the apartheid cases allowing many of the perpetrators to get away with it."
In 2017, Judge Billy Mothle, who led an inquest into Timol's death, found the activist had been murdered and recommended the NPA probe apartheid-era cop Joao Roderigues' role in his death.
At the time of his death in 1971, Timol was in custody.
Officers who interrogated him, including Roderigues, claimed he threw himself out of a window from the 10th floor of John Vorster Square, now the Johannesburg Central police station.
A 1972 inquest found Timol had committed suicide, however, after the family disputed this, it was reopened in 2017 and it was found he was murdered.
Mothle also ruled Sons and Els should be charged for perjury.
NPA spokesperson Phindi Mjonondwane told News24 it had decided not to prosecute as the State must prove the evidence they gave was intentionally false.
"Both Mr Els and Mr Sons gave three standard answers regarding their knowledge of the assault of detainees - that they were not aware of the assaults on detainees, that they can't remember or that they read about them in newspapers," she said.
Mjonondwane said there was "also a technicality" in that Sons was not properly put under oath by a judge.
"He only warned Mr Sons about the import of the oath until well into his evidence. He informed the judge that his legal representative did not explain the import of an oath to him. A witness is only competent to testify if he appreciates the difference between the truth and untruth.
"Section 319 of Act 51 of 1977 [making conflicting statements under oath] is not applicable as it has not been shown that they have deviated from their previous statements."
She said the assault charges arose out of the torture and assault of detainees by members of the Security Branch during interrogation between 1971 and 1982.
"In so far as the assault charges at John Vorster Square are concerned, prescription has set in, as a period of 20 years has passed since the commission of the offences in 1982/83."
Cajee had been kept abreast of developments and afforded a hearing at the highest level in the NPA, from the investigation process to the decision in the case, Mjonondwane said.
"He is aware that he is at liberty to challenge this decision by making representations to the head of the NPA and National Director of Public Prosecutions."
Cajee and the Timols described the decision not to pursue the charges as bizarre.
"Judge Mothle found that police records conclusively reflected that Els was present when Professor Kantilal Naik, a fellow detainee, was subjected to the helicopter method of interrogation, after which he subsequently lost use of his hands," the family’s statement said.
"Els and Sons were both found to have lied under oath indicating that they had no knowledge of the torture of detainees and had only learnt of the assaults from reports in the media.
"Five witnesses subsequently came forward after Sons' testimony and filed affidavits to the effect that they too had been assaulted by Sons."