I have the same bug, related to the kill of the Master Thief at the Beginning of the Game near Riverwood. But i don't have any of the Mods blamed for this Bug installed, so i wonder if its simply an random encounter or which mods also bring this master thief up at the beginning o.o. I'll go now through my installed mods and search for the 'victim' and i hope that there is an easier fix via console or via the unoffical skyrim patch soon.