I guess this must be one of those unsolved mysteries that will never be answered and we will never know the whole truth, just like JFK.
Anyway IMHO I think Kurt Cobain was in fact murdered by someone. There's just too many details that don't make sense.
The suicide note says nothing about Kurt wanting to kill himself and also the last three lines appear to have been written by someone else.
If Kurt Cobain wanted to kill himself do you think he would inject himself with a lethal dose of heroin and then shoot himself with a shotgun?
I think he was going to divorce Courtney, she knew it and she just couldn't accept it, so she sent someone to kill him.
BTW, Courtney Love is a bitch!