You can start this quest in Windhelm by visiting the graveyard on the left side of the town. It won't show up right away though, but after you've visited Windhelm 2-3 times you can go to the graveyard and see a gathering of people (I left and waited for 24 hours, then went back until the gathering of people showed up in the graveyard).
Once the poeple show up, head over to them and you'll see a woman has been murdered. The guard nearby will ask if you saw anything, and from there you can offer to help out.
Note: I'm fairly certain this quest is GLITCHED if you advance too far into the game. For the life of me I can't get it to show up on my higher level character. I got it to show up on a lower level character fairly easy, so BE AWARE that this can happen...
The guard will reluctantly let you help and will ask you to question the three witnesses nearby. Go up to each of them and ask if they know anything. They will each give you vague details at best, so go back and reporrt to the guard. He'll listen but will tell you that you need to talk to Jorleif if you want to OFFICIALLY help investigate.
Jorleif is in the Palace of the Kings , so head over there and talk to him. He'll gladly accept your help, so now your officially looking into this and are not some nut off the street. Go back and tell the guard by the crime scene that you have permission to help. He'll mention two things: that Helgrid took the body to the nearby Hall of the Dead for burial and that he noticed a path of blood leading away from the crime scene .
You can go talk to Helgrid now to learn that the attacks were done with an ancient Nord weapon, but she isn't any help after that. Also, be sure to follow the blood trail to a house in the northwest part of the city named " Hjerim ". It will be locked with a master lock . You can then ask either the guard or Jorleif how to get into it. The'll mention Tova Shatter-Shield has the key.
Go talk to Tova now (she lives just south of Hjerim) and tell her you're trying to find the killer and she'll give you the key. With the key you can easily enter Hjerim, so head over there. Upon entering you'll see the blood head to a chest . Investigate and then open the chest. What you want to pick up and read here (and take) is the " Butcher's Journal 1 ".
Now; head over to where the cabinents are. There is a small shelf between the cabinents you can investigate. You'll find more fliers, but the investigation will note that one stack of them is disheveled. That is because there is a " Strange Amulet " here. Go ahead and pick it up. Now investigate the right cabinent and reveal the hidden wall behind it. Yuck, you'll have uncovered the altar where this psycho is doing his "magic". Investigate the altar and take the " Butcher's Journal 2 " from it. You can exit the house now.
Now either go talk to Jorleif or any guard (it really doesn't matter which) to get two new questions to ask them. The first will be about the "Beware the Butcher" posters that you found. Turns out a woman named Viola has been putting them up around town and someone (likely the butcher) has been taking them down. The second question involves the amulet, and learning what it is. You will be told to go visit Calixto at his shop to help identify it.
Ok, let's go talk to Viola now. She's usually either in her house or Candlehearth Hall , but you should have a pointer for both her and Calixto to help you find out where they are. She'll mention she's been trying to learn who the butcher is for awhile now and suspects the court wizard, Wuunferth , of being a Necromancer.
You can go talk to Calixto now (he's either at his shop or out taking a walk) and he'll note that the amulet is passed down from court wizard to court wizard as a ceremonial token, and should belong to Wuunferth. He will also try to buy it from you for 500 Gold (you should sell it - trust me). Well now, the evidence is PRETTY strong against Wuunferth at this point. So much so that the game tell you to go talk to Jorleif now and present your case.
But wait! You have two options here. You can either to talk to Jorleif OR you can go confront Wuunferth yourself. This choice actually puts you down two VERY different paths. The "best" choice would be to go talk to Wuunferth, but again, you don't HAVE to. Follow the walkthrough in the box below if you choose to go talk to Jorleif first. If not, skip the box and follow that section!
Go tell Jorleif that you think Wuunferth is the killer. He'll ask you for proof and you'll tell him of the journals and amulet, which is good enough for Jorleif! He will thank you and the quest will pop up on the screen as complete. You can head out from here, but its interesting to follow Jorleif as he arrests Wuunferth and has him thrown in jail (the jail is in the Barracks off the Palace of Kings by the way).
Now, you may think the quest should be over by now except it ISN'T! You can either wait awhile or (what I'd do) go somewhere and let three days pass by waiting and come back to the city at nighttime. Pass by the left side of Candlehearth hall and you'll see ANOTHER woman murdered! Gah! Talk to the guard nearby who will question whether you even captured the right person (obviously you didn't!). He'll then tell you to go and talk to Wuunferth in the prison.
Go talk to Wuunferth and he'll mock you a bit before cooperating with you. The topic will steer to the journals and amulet you found, and upon | | hearing its description, he will do some calculations and tell you the killer is going to strike TONIGHT! You are now caught up with the path of "confronting Wuunferth instead of telling Jorleif HE is the killer". Read below (which will repeat SOME info) and continue with the quest.
Well, so you've either made a terrible mistake and followed the guide through the box to here OR you went and talked to Wuunferth first! Good.
For those who are just now trying to talk to Wuunferth , you can usually find him in the Palace of Kings or in his bedroom above the Palace of Kings (take the first left door after entering, his room is in the far back). He will tell you that he too has been investigating the murders and will ask you to describe the ring to him. Upon hearing your description, he'll advise it is the Necromancer's Amulet , and will do some quick calculations and tell you the murderer will strike again... tonight!
Your objective will now be to patrol the stone quarter to find the murderer. Leave the Palace and make it night if it isn't already ( move time forwards to 11PM and you should be good) and then explore around the merchant's quarter. You'll likely find a High Elf named Arivanya (or, if this is the second victim, an Argonian named Shavee ) standing haphazardly about.
Wait around and soon you'll see... Calixto ? Watch and Calixto will get into a sneaking stance, draw a weapon, and advance on Arivanya. Quick, go save her by attacking Calixto ! Calixto will attempt to run towards Hjerim, but you should be able to take him out (any guards in the area will come help you). Be sure to loot his body thoroughly to get several goodies, including the enchanted Necromancer's Amulet back (better than ever!) .
From here, you can go talk to Jorlief to officially end the quest, but I would also recommend heading on over to Calixto's house ! You can easily open it with the key you found on his body. Inside you can freely steal from his shop of knick-knacks if you wish, but the most interesting thing in here is up on the second level, where you can open a chest and find the " Butcher's Journal " to see WHY Calixto was doing what he was doing....