When South African police raided the warehouse of a company called Tradefin Engineering, a manufacturer of pipes and valves, in September 2004, they discovered stacks of shipping containers eleven stories high loaded with parts marked for reassembly in Libya, that would have given the Libyans the ability to process enough enriched uranium for several nuclear bombs. Tradefin had become part of a vast, worldwide network supplying parts for the manufacture of nuclear weapons under the direction of A.Q. Khan, the former architect of Pakistan’s nuclear program.

But the three men running the Tradefin operation were not new to the nuclear black market. All three had previously worked with the South African government obtaining, through underground trafficking networks, critical technology for South Africa’s own top-secret nuclear weapons program in the mid 1980s.

South Africa’s nuclear bomb program was conducted out of a top-secret facility called Kentron Circle, located in the broad savannah about thirty miles from Pretoria. Its still there, a conical concrete bunker, now empty, hidden in the hills about a ten-minute drive off the main road leading to Botswana. Inside, a team of twenty scientists, working in secrecy, ultimately succeeded in building six nuclear bombs, working from designs and technology smuggled in from illicit dealers around the world. At the time, South Africa’s apartheid government was operating under severe international sanctions.

“We would tell them what we needed, and two or three weeks later it arrived,” recalls Andre Buys, who was one of those scientists. Buys, now a Physics professor at Pretoria University, has since become active in global non-proliferation efforts. “[When] such equipment arrived, I’d say ‘thanks’. I didn’t ask how ask how it got there … Sanctions busting was a big business back then.” Sanctions-busting brought everything from oil to consumer goods into South Africa’s black market. The most sensitive and secret component of that illicit trade were the black market connections supplying the material and know-how for South Africa’s nuclear weapons program.

Among those sanctions-busters were three business-savvy engineers who would later surface as key players in the A.Q. Khan network: Gerhard Wisser, organizer of the Tradefin deal; Daniel Geiges, his chief engineer; and Johan Meyer, the owner of Tradefin.

In the 1980’s Wisser’s firm, Krisch Engineering, was a “key supplier of equipment” to the South African Atomic Energy Corporation, according to Wisser’s plea agreement filed with South African prosecutors last year. The energy corporation was run by the apartheid government of the time and was one of the main companies responsible for the development of the secret nuclear weapons program at Kentron Circle—the place where Buys helped to build South Africa’s nuclear bombs.

Daniel Geiges, Wisser’s aide-de-camp and chief engineer, began working for him in 1981 and would later manage the Libyan project at Tradefin. They worked together to import technology to the South African nuclear program in defiance of international sanctions. While at the AEC, Wisser met the man who would some two decades later nickname their joint nuclear enterprise, “the beast.” Johan Meyer was working for the South African Uranium Corporation—the company responsible for mining and processing the uranium that would be used in the nuclear weapons being assembled at Kentron Circle.

Wisser is German and Geiges is Swiss; both had become residents of South Africa, which at the time had what amounted to an open door policy for white immigrants, no questions asked. Meyer is a native South African afrikaneer.

Their trafficking was not an exclusively one-way enterprise. Wisser and Geiges were also in the business of exporting South Africa’s own sensitive nuclear technology. And one of their key overseas clients was AQ Khan in Pakistan. Those dealings are laid out in the indictment of Daniel Geiges. It was all perfectly legal: South Africa’s government-owned arms company made a profit too.

Over some twenty years, Wisser, Geiges, and Meyer were participants in a global underground network that helped facilitate some of the most egregious violations of non-proliferation laws in history. They enabled not only South Africa to build its bombs, but also helped AQ Khan himself develop Pakistan’s nuclear weapons program.

By 1989, South Africa began its historic revolution. Nelson Mandela was freed from twenty-seven years in prison, and by 1993 was preparing to take office as the country’s first democratically elected president. Shortly before Mandela was inaugurated, then-President FW deKlerk informed the IAEA that the country had “decommissioned” its nuclear weapons. This was unprecedented; South Africa was the first country to have built, and then destroyed, a nuclear arsenal.

But this epic change did not eliminate the trafficking networks that had evolved over the many years of South Africa’s international isolation. Men like Wisser, Geiges, and Meyer were left without the lucrative black market deals that had made them wealthy. By the end of the century, the three were working together once again, manufacturing and exporting parts for A.Q. Khan’s global nuclear weapons manufacturing scheme. Wisser and Geiges were paid $1.5 million for their work on behalf of A.Q. Khan, with checks drawn on Libyan, Pakistani and Middle Eastern banks; another $1 million was paid to Tradefin’s owner, Johan Meyer.

Mark Schapiro specializes in international and environmental stories. His award-winning work appears in all media: in publications such as Harpers, The Atlantic, Mother Jones and Yale 360; on television, including PBS FRONTLINE/World and KQED; on public radio including Marketplace; and on the web. He is currently writing a book for Wiley & Co. investigating the backstory to our carbon footprints. His previous book, "EXPOSED: The Toxic Chemistry of Everyday Products and What’s at Stake for American Power," reveals the health and economic implications of the tightening of environmental standards by the European Union.