Four years after the CIA was forced to reveal the identities of three Swiss engineers they used to do major damage to nuclear weapons developments programs in Libya and Iran, the three Swiss men were finally assured that they would not go to jail. This was apparently part of a deal between the CIA and Swiss prosecutors. The three Swiss engineers were mercenaries who had helped Pakistan develop nuclear weapons but later agreed to work against Pakistan when tracked down by the CIA and Swiss investigators.
This was done by getting to one of the engineers working for the Pakistani Khan network (named after scientist Abdul Qadeer Khan, who led development efforts for Pakistani nuclear weapons) to secretly switch sides. The CIA basically hired Swiss engineer Friedrich Tinner, and his two sons, to feed the Khan network and its customers defective (in subtle ways) nuclear weapons components. From 2001-4, the Tinners worked under CIA direction. This caused Libya to drop its nuclear weapons program and delayed work in Iran.
But for most of the last decade the Tinners have been prosecuted in Switzerland for their work with the Khan network. The elder Tinner began working for Khan in the 1970s, helping to steal European nuclear technology for the Pakistani weapons program. This relationship expanded in the 1990s, when Abdul Qadeer Khan began making money on the side by selling nuclear weapons technology to anyone who could afford it and was discrete (like Libya, Iran, North Korea, and Iraq). The CIA effort to get details of the Khan network, and take it down, led them to Tinner, whose willingness to collaborate helped bring down the Khan network.
The CIA paid the Tinners $10 million for their work and have fought to keep them out of jail ever since. Four years ago details of the Tinner operation were leaked to the media. The CIA then proceeded to try and keep secret the methods and contacts it used to uncover and destroy the Khan network, as well as how it sabotaged components. All this information can be used again, if it doesn't get published in the mass media first.