I am the new magistrate of Southshore, recently assigned after the assassination of the previous magistrate. The assassins were never found, but through our investigations we're almost certain they were hired by the Syndicate - a group of thieves led by villainous nobles of the now fallen kingdom of Alterac.
The Syndicate has a camps in Sofera's Naze and Corahn's Dagger, north and west of the Horde-occupied Tarren Mill. Slay the Syndicate members you find in these camps.
Thank you, <name>. Although they may still be lurking about, we hope that some of the thieves and footpads you slew were responsible for the last magistrate's death. But even if they weren't, the Syndicate is a taint on this land and a stain on the human race.