When the heir to the throne of Austria-Hungary was assassinated in 1914 what country was blamed?

When Archduke Franz Ferdinand of Austria-Hungary was assassinated in 1914, Serbia was blamed for the act. The assassin, Gavrilo Princip, was a member of a nationalist group seeking to promote Serbian interests and independence from Austro-Hungarian rule. This event set off a chain of diplomatic crises that ultimately led to the outbreak of World War I.