This quest has got to be one of the glitchiest quests I have ever seen in any game.

I went to the graveyard in Windhelm to start the quest. Susanna the Wicked (the dead body) is there, Helgird is there, Calixto Corrium is there, Silda the Unseen is there, but the guard you talk to to start the quest is not. I tried waiting for extended periods of time, fast-travelling then coming back, leaving and re-entering Windhelm, and talking to all the guards I see in Windhelm. Nothing works. This needs to be patched ASAP.