November 17 was the 20th anniversary of the Czech "velvet revolution." One of the events that triggered it was the spread of a rumor alleging that mathematics student Martin Smid had been beaten to death by police. Smid, however, was very much alive, and he still is. To this day, he has no idea how his name got attached to the rumor. From agonist.org:
After a bloody crackdown on a non-violent student march in Prague on November 17, 1989, a woman falsely claimed that the riot police had beaten to death her friend, a 19-year-old mathematics student named Martin Smid.
Reports of the alleged death spread like wildfire, rousing ordinary people from their lethargy and igniting the peaceful coup that brought back democracy to Czechs and Slovaks.
Twenty years later, the motivations of the women's false claim - and the role of journalists in spreading it - remains clouded in mystery.
There's more about the Martin Smid rumor at radio.cz.