Agent Farewell the Disillusioned Communist
Vladimir Vetrov (or Agent Farewell as he was called by the French DST) was not the greatest spy of the 20th century, but his information was instrumental in stopping the Soviets from stealing important technological secrets from the West. He betrayed his country for purely ideological reasons and not money which may have been why he was so successful. However, in the end he caused his own downfall.
Vladimir studied electronic engineering in college in the U.S.S.R. and then joined the KGB after graduation. He was sent to France as a Line X officer part of Directorate X which was a program geared toward stealing Western technological secrets. After five years in France he returned to Moscow where he was promoted in Directorate X to where he was evaluating all information that was coming from Line X officers around the world.
It was around this time that he started to lose faith in the communist system and decided to begin working with the DST (Direction de la Surveillance du Territoire). In 1981 and 1982, Vetrov gave up over 4,000 documents to the DST, including the names and covers of 250 Line X agents around the world. He gave up all the details of the Directorate X program. It was based on his information that 47 agents were removed from France, and more than 100 more were expelled from other Western countries.
In early 1982, the French told Vetrov to go silent out of fear that he would be discovered for doing too much at once. This sent Vetrov into a depression that caused him to drink excessively. He ended up stabbing his mistress while the pair were together and then stabbing a man who knocked on his car window (believing his cover had been blown). He was sentenced to 12 years in prison for the crimes. While he was in prison the Soviets realized that he was a double agent and executed him in 1985.