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
1978 Balkan Bulgarian Tupolev Tu-134 crash 1978 Balkan Bulgarian Tupolev Tu-134 crash The 1978 Balkan Bulgarian Tupolev Tu-134 crash was an accident that occurred on 16 March 1978, when a Balkan Bulgarian Airlines Tupolev Tu-134 airliner on an international flight from Sofia, Bulgaria, to Warsaw Airport, Poland crashed. On departure from Sofia, the aircraft was climbing to , but at it turned on a heading of 050. It turned again to 270 then began an abnormal descent. The aircraft crashed near the village of Gabare, 130 km northeast of Sofia. All 73 on board died. It was never established what the nature of the emergency was