Theresa Squillacote, 39, a Pentagon employee, her husband, Kurt Stand, 42, a union representative, and James Clark, 49, a private investigator, have all been charged with passing secrets to the Soviet Union and East Germany during the Cold War. They could face the death penalty. The methods the FBI used to catch them, however, were bizarre, not to say unethical.
The story began innocently enough in 1995, when Ronnie Kasrils, South African deputy defence minister and revolutionary par excellence, received a letter from an American fan. It praised Armed and Dangerous, a book Mr Kasrils, a Communist and former ANC guerrilla leader, had just published about his deeds in the struggle against apartheid.
Nicknamed the "Red Pimpernel", Mr Kasrils somehow brings a cuddly naivety to the bloody business of war; some have described his book as pure Boy's Own adventure. But the letter, signed Lisa Martin, was rapturous. Clearly disillusioned with Mom and Apple Pie, she complained bitterly about the "spiritual death" of the US, lamented the fall of the Soviet Union and described South Africa as a bright light on a dismal horizon.
Mr Kasrils, who had so recently traded the bush and camouflage fatigues for an office and a sober suit, was flattered. Two months later, when the revolutionary was sending out his Christmas cards, he dispatched a little "thank you".
That was that for Mr Kasrils, until he and his wife woke up last week to hear a newscaster announce that a US spy ring had been smashed with the involvement of a senior South African government official. "We wondered who that could be," said Mr Kasrils. He soon found out when the Deputy President, Thabo Mbeki, called to ask if he remembered receiving a letter from Ms Martin - an alias, it turns out, of Ms Squillacote's.
Without his permission or knowledge, Mr Kasrils has for the past two years been central to the FBI's operation against the alleged spies. The agents appear to have noted his brief correspondence with Ms Squillacote while bugging her home, and hit upon the ruse of using him to reel in the trio, who after years of smuggling information all over the globe in book-bindings and hollow dolls' heads, were woefully short of a spymaster.
The trio, motivated by hatred of capitalism rather than material gain, were thrilled when apparently asked to spy for South Africa, and arrested when persuaded to steal Pentagon papers.
This weekend the US and South African governments are struggling to kiss and make up. Mr Kasrils is furious - not least at the FBI's claim that he and the South African government were part of the set-up, and that he even passed on the letter from "Ms Martin". This has been vehemently denied in Pretoria, along with claims that Ms Squillacote offered to spy.
The FBI has now admitted South Africa was never aware of the investigation, and has expressed regret for "any embarrassment". This appears to fall short of the minister's demand for a formal apology for impersonation and forging his signature on letters to the accused, which he calls "a misappropriation of the South African flag, my name and [my] office".
Would the Communist terrorist turned politician have helped the agents of the world's most powerful capitalist state if he had been asked? "Absolutely not. Quite frankly, I feel for the people entrapped using my name . . . people who thought they were helping the Democratic Republic of South Africa."