What country was blamed for killing of Franz Ferdinand?

Serbia was blamed for the assassination of Archduke Franz Ferdinand of Austria in June 1914, which set off a chain of events leading to World War I. The assassin, Gavrilo Princip, was a member of a nationalist group seeking to liberate Slavic peoples from Austro-Hungarian rule, and he was motivated by Serbian nationalist sentiments. Austria-Hungary used the assassination as a pretext to issue an ultimatum to Serbia, ultimately leading to the outbreak of the war.