The bit where it says "in Serbia" seems to be talking about where the assassination happened. That could potentially refer to where he was Archduke instead, but that would be a really odd way to construct the sentence if so, and in any case would still be wrong.
> Franz Ferdinand Carl Ludwig Joseph Maria (18 December 1863 – 28 June 1914) was an Archduke of Austria-Este, Austro-Hungarian and Royal Prince of Hungary and of Bohemia [1]
Even if the author meant that Franz was an Archduke in Serbia, he would still be mistaken.
