Two Thai nationals appear in court in Johannesburg on charges of alleged involvement in the illegal rhino horn trade.
South African game farm owner Marnus Steyl also appears in the dock.
The defendants are believed to have used trophy hunts as a front to launder rhino horns and transport them to Southeast Asia.
The case is important because for the first time it implicates a suspected top-level international crime boss, as well as South Africans licensed to keep rhino who have been killing them for profit.
Animal rights activists outside court, protesting the surge in rhino poaching, are optimistic.
(SOUNDBITE)(English) MIRANDA JORDAN, ANIMAL RIGHTS CAMPAIGNER:
"What we are extremely pleased is what we have seen since the arrest on Friday a very, very quick move as far as the arrest of Marnus Steyl, and I think that was very, very important because Marnus Steyl plays a major role in the syndicate. He has been providing both the rhino and the lion bones."
South Africa allows for one rhino kill per person per year, and the Environment Minister says the country is working to track movement of the horns.
(SOUNDBITE)(English) SOUTH AFRICAN ENVIRONMENT MINISTER, EDNA MOLEWA:
''Every hunt that has been made, if there is movement out of the country it's going to be recorded, it's going to be registered, we have started working with other countries like Vietnam, like China whom we have had meetings with two days ago, where there is an agreement that we work together in terms of monitoring these movements."
South Africa is home to 90 percent of Africa's white rhino population.
Rhino horn has been used in Chinese medicine for centuries and killing rhino for their horns is lucrative business.
Nick Rowlands, Reuters.