“Evidence has been sitting there since the attack on Magaqa,” Ms. de Haas said.
Thabiso Zulu, an A.N.C. member and whistle-blower who helped Mr. Magaqa expose corruption in Umzimkhulu, said he and others had provided the authorities with evidence in the case long ago.
“All we can say is that the A.N.C. is going into an election soon, and they’re running on a ticket of clean government and anticorruption, so something had to give,” Mr. Zulu said on Monday, referring to national elections scheduled for May 8.
For nearly a year, Mr. Zulu and Les Stuta, another A.N.C. whistle-blower who helped Mr. Magaqa, have lived in hiding because of constant death threats.
President Ramaphosa’s government has resisted a recommendation by the Office of the Public Protector, a government agency that investigates corruption, to provide police protection for Mr. Zulu and Mr. Stuta. Mr. Ramaphosa’s police minister has gone to court to challenge the Public Protector’s recommendation, and Mr. Ramaphosa is waiting to see the legal outcome, his office has said.
In December, the Public Protector released a report calling on the police to investigate the killings of Mr. Magaqa and others in Umzimkhulu.
And in February, the public protector, Busisiwe Mkhwebane, stepped up the pressure on Mr. Ramaphosa, singling out the president and his police minister for failing to carry out her recommendation as required by law. “You should be respecting the Constitution and the rule of law,” Ms. Mkhwebane told the police minister.
Mr. Stuta, one of the two whistle-blowers, said Monday that he still feared for his life despite the arrests. Allies of the two arrested men were still out there, he said.
“Hit men are still all over the show,” he said.