Board Thread:Skyrim/@comment-14027812-20131117233629/@comment-26213507-20190707012905

Make sure you don't have the quest "Blood on the Ice" active. Nilsine is one of the potential targets for the murderer to kill later in the quest, so make sure to kill him before worrying about Muiri, since it sounds like she is getting murdered every time you return to Markarth.