So, I decided to try a different approach to this quest, mostly just for kicks. Rather than stop the killer on the first go, I decided to blame the wizard, got him locked up, and then came back to finish up the second part of this quest. Anyway, when I got to the part where I stop Calixto, he started stalking after someone like he has done for me always. Yet, this time, he followed through with his backstab animation without actually backstabbing anyone. It was rather odd. I'm just wondering if this is normal for those who choose not to kill him the first time around, as I've never done this quest this way before.

Maybe he ran out of victims? I believe if you don't kill him once you know who the killer is, he continues to go on a killing spree.

Also, if you don't kill him, he can actually outrun you and run into Hjerim and become aggressive. When that happens, you can't kill him.

Other players will have other suggestions for sure.

Well, I seem to have come across an issue that has not been reported to my knowledge. It seems the rise in the east quest conflicts with blood on the ice, at least in this case. Since he already did away with his last victim, the game supposedly chooses a random female npc for the next kill. Anyway, it looks like the game chose the east empire chick that sends you off to Japhet's Folly, but until I progressed that quest far enough, the girl won't spawn. Odd that blood on the ice would pick an npc that's not even technically in the game yet.

So anyway, I did rise in the east quest far enough to cause that girl to spawn, and calixto finally had someone "visible" to kill. Too bad he ran into another issue, that being she is marked as essential. Lol, oh well, the rest of the quest went without a hitch. He ran into the house and I killed him. Leave it to Bethesda to make all sorts of bugs to appear when I decide to finish a quest a slightly different way.

I've done the whole blame the wizard and get him in jail. Then after the high elf dies I'll go find out from the wizard about the butcher's patters. I've always then killed him before he struck again.

But usually so I don't end up with unwanted crap in my inventory I don't take the amulet. I only take one note. I'll go directly to the old woman after getting into Hjerim. From there talk to the wizard and wait that night for the butcher. Seems to be the only way I can complete the quest without it getting bugged.

I also did the 2nd part as I was curious. When I saw the next victim was the smithing girl and was glad. I just let him slit her throat.

You probably already know this, but if you talk to Calixto before you talk to the old woman, you can sell the amulet to him and get it changed into the non-quest Necromancer's Amulet. Of course to retrieve it you have to kill him, so you can choose when to collect it (if you're not going to keep it you can sell it for a couple grand if you have high enough Speech and the selling perks).