I cannot "examine crime scene" so I can't complete the quest. This is really getting frustrating. This is the second playthrough where I have been unable to acquire the house in windelm because of this quest.

I just figured this one out. The marker was hovering over the site where the body was so I just assumed I had to activate the crime scene some how. You should make the marker hover over the blood trail or the door to the house.

Yup it's annoying and following the trail isn't exactly obvious but you solved it well done.