Ricin immunogenic in mice, rabbits, and humans. It has completed two successful clinical trials. Ricin has been involved in a number of incidents. In 1978, the Bulgarian dissident Georgi Markov was assassinated by Bulgarian secret police who surreptitiously shot him on a London street with a modified umbrella using compressed gas to fire a tiny pellet contaminated with ricin into his leg. He died in a hospital a few days later and his body was passed to a special poison branch of the British Ministry of Defence (MOD) that discovered the pellet during an autopsy. The prime suspects were the Bulgarian
People's Republic of Bulgaria his leg with the tip of an umbrella. Markov died shortly afterwards of ricin poisoning. He was the victim of the Bulgarian secret service, as confirmed by KGB documents revealing that they had jointly planned the operation with Bulgaria. The Bulgarian People's Army sided with the Soviet Union and the Afghan communists during the Soviet–Afghan War in Afghanistan fighting the jihadist guerrillas from 1982 until its withdrawal in 1989. By the 1980s, the conservatives controlled the government. Some social and cultural liberalization and progress was led by Lyudmila Zhivkova, Todor's daughter, who became a source of strong disapproval and annoyance