Todor Zhivkov to 1988, Bulgaria won an unprecedented 153 Olympic medals and numerous European and world competitions in sports as diverse as volleyball, rhythmic gymnastics and wrestling. Dissent was punished under Zhivkov's rule. The CSS was a feared tool of control, and overt opposition largely stayed underground until the late 1980s. In 1978, the Bulgarian dissident Georgi Markov was assassinated in London by an agent who stabbed him with an umbrella tip which implanted a very small ricin ball. According to former KGB general Oleg Kalugin, this was requested by Zhivkov and either performed by the KGB or it assisted the CSS;
Ricin was charged with manufacturing ricin in his dorm room, as well as the intent of "[using] the ricin on another undergraduate student with whom he had a relationship". Mohammed Ali from Liverpool, England was convicted after attempting to purchase 500 mg of ricin over the dark web from an undercover FBI agent. He was sentenced, on 18 September 2015, to 8 years' imprisonment. Ricin Ricin ( ), a lectin (a carbohydrate-binding protein) produced in the seeds of the castor oil plant, "Ricinus communis", is a highly potent toxin. A dose of purified ricin powder the size of a few grains