Blood on the Ice
I had many problems with this quest, especially the part where you patrol the Stone Quarter at night. Nothing showed up, so I checked out the abandoned house. This finally triggered the guy; Went back to Candlehearth, then back to the house, where I killed him. I still have the weird amulet or whatever it is, it was never changed to Necro amulet. I can't sell it or drop it, but at least it weighs zero.
“He who makes a beast of himself gets rid of the pain of being a man.” Samuel Johnson