Bulgaria–United States relations to work. Bulgaria became a member of the Warsaw Pact on May 14, 1955. Though no Soviet troops were stationed on Bulgarian soil, in 1968, Zhivkov sent a Bulgarian division to join Polish, Hungarian and Soviet troops to crush a popular uprising in Prague. In 1978, the Bulgarian secret police were implicated in the assassination in London of Georgi Markov, a Bulgarian dissident who was a correspondent for the BBC World Service, Deutsche Welle radio and the U.S. sponsored Radio Free Europe. Markov was assassinated with a poisoned umbrella on September 7, Zhivkov's birthday. The rise of democratic movements across
Bulgarian umbrella Executioner". A type of this umbrella is used even in poliziottesco Italian movie The Police Can't Move in 1975. A Bulgarian umbrella was featured in the 2013 "The Americans" episode, "The Clock". A similar assassination (and attempt) were central to the plot of the 1978 "Quincy, M.E." episode, "Hot Ice". The 2010 episode "Marionette" of "Fringe" begins with an organ thief administering a paralytic with an umbrella. In the AMC series Breaking Bad, season 2, episode 2, Walter White shows his accomplice, Jessie, a small bag of castor beans which he explained, the ricin can be extracted and which was