Ricin the attack on Georgi Markov another Bulgarian defector, Vladimir Kostov, survived a similar attack. Kostov was standing on an escalator of the Paris metro when he felt a sting in his lower back above the belt of his trousers. He developed a fever, but recovered. After Markov's death the wound on Kostov's back was examined and a ricin-laced pellet identical to the one used against Markov was removed. Several terrorists and terrorist groups have experimented with ricin and caused several incidents of the poisons being mailed to U.S. politicians. For example, on May 29, 2013 two anonymous letters sent to
Ricin At that time it was being considered for use either as a toxic dust or as a coating for bullets and shrapnel. The dust cloud concept could not be adequately developed, and the coated bullet/shrapnel concept would violate the Hague Convention of 1899 (adopted in U.S. law at 32 Stat. 1903), specifically Annex §2, Ch.1, Article 23, stating "... it is especially prohibited ... [t]o employ poison or poisoned arms". World War I ended before the United States weaponized ricin. During World War II the United States and Canada undertook studying ricin in cluster bombs. Though there were plans for