The 67-year-old singer believes Jean de Breteuil, who was a drug dealer, was behind the Doors singer's early death in 1971 because he supplied the late star with heroin that allegedly ended his life at the age of 27.
Speaking in Mojo magazine, she said: ''He went to see Jim Morrison and killed him. I mean I'm sure it was an accident. Poor b*****d. The smack was too strong? Yeah. And he died. And I didn't know anything about this. Anyway, everybody connected to the death of this poor guy is dead now. Except me.''
Marianne was staying at a Paris hotel with Jean when he went to visit Jim at his apartment, where he was later found dead in his bathtub.
She added: ''I could intuitively feel trouble. I thought, 'I'll take a few Tuinal [barbiturates] and I won't be there.' ''
Jim's exact cause of death is unknown as no autopsy was performed at the time because the medical examiner stated there was no evidence of foul play.
Meanwhile, Marianne also went on to discuss the late Amy Winehouse, who also died at the age of 27 from alcohol poisoning, and claimed the singer disliked her because she knew about her substance abuse.
She explained: ''Amy was very, very wary of me. She knew that I knew and she didn't want me to say anything. There's a level of narcissism which is all mixed up with self-hatred. I know it well.''