
The Coroner who preformed Kurt's autopsy had once promoted Nirvana concerts. The Coroner said about Kurt's death "There was absolutely nothing that indicated it was anything other than a suicide." (1) It's leap of faith, that someone who once promoted concerts for bands would now risk his job, prison, and public disgrace, in order to cover up a murder. I have promoted numerous concerts. Would I aid in covering up a murder? No. As a promoter you don't have that type of relationship with the bands you promote.
At any rate suicide is listed as the cause of Kurt death on Kurt's death certificate.