So I had a bug with this quest where I couldnt pick which of the 2 people to accuse for the murders.
I found this which told me how to fix it and still buy the house:

• Complete the quest: Type "completequest ms11" and "completequest ms11b" in your console.
• Buy the house: Type "setstage a7b33 10" in your console.
• First buy "clean up that murderer's mess" and then the rest of the home decoration or type "df492.disable" in your console.
• Clean the fog, broken glass, etc. in the house: Type "df495.disable" in your console.
• Get the Necromancer Amulet: Type "player.additem c891d 1" in your console.

But now both the 2 suspects are still alive.
How can I console kill one of them?

Then it will be fully complete