Kurt, considering he had bipolar (or just suspected bipolar?) and his death was ruled as suicide. It is interesting, but he wasn't murdered, there's no solid (as far as I know) evidence against Courtney anyway.
I'm a Nirvana fan, so this is my kind of topic. I had actually considering posting this earlier, actually.
Anyways, honestly, I think it was a suicide. Kurt had been battling depression practically his whole life, and he had been a heroin addict since 1986 and there were many times he would overdose, and heroin practically controls you as you take more and more.