Money from the project found its way into the bank accounts of politically connected individuals and companies, including one of the Gupta brothers, Atul, according to prosecutors. The project was backed by two high-ranking African National Congress politicians close to the Guptas: Mosebenzi Joseph Zwane, who later became Mr. Zuma’s minister of mineral resources, and Ace Magashule, the party’s current secretary general. The Gupta brothers are now believed to be in Dubai.

Eighty to 100 black farmers who were supposed to become beneficiaries of the project ended up receiving nothing — an outcome that, to many, symbolized the corruption that has flourished under the A.N.C., the party that has ruled South Africa since apartheid ended in 1994.

For years, the problems surrounding the dairy project had drawn the attention of the South African news media as well as investigators from the National Treasury. But the authorities made arrests in the case only in February, after Mr. Zuma was ousted as president.

The case is regarded as a test of how far his successor, Cyril Ramaphosa, will be able to carry out his pledge to root out corruption in government.