Brittany Murphy's mother claims reports suggesting her daughter was poisoned are "madness".
The '8 Mile' actress was found dead at home in December 2009 and the Los Angeles Coroner ruled her death was accidental, caused by acute pneumonia and anaemia, with her husband Simon Monjack also succumbing to the same illnesses five months later.
The late star's father, Angelo Bertolotti, wasn't convinced by the findings and ordered a new toxicology report after sending samples of his daughter's hair for independent analysis, which supposedly showed the presence of 10 heavy metals commonly used in rat poison.
Brittany's mother Sharon Murphy has now penned an open letter slamming her ex-partner's "inexcusable" publicity-seeking claims, insisting he was never a father to the actress since he abandoned her as a baby.
She wrote in a statement published by The Hollywood Reporter: "I have no choice now but to come forward in the face of inexcusable efforts to smear my daughter's memory by a man who may be her biological father but was never a real father to her in her lifetime. Angelo Bertolotti has relocated to California in his old age to claim he is here for Brittany, as he never was in life.
"He has made outrageous statements over the past few years, culminating in this latest madness: that my darling daughter was murdered. His claims are based on the most flimsy of evidence and are more of an insult than an insight into what really happened."
Sharon also dismisses the legitimacy of the lab which conducted the research, claiming their allegedly un-scientific experiment is a total "ethical violation" of her daughter's memory.
She strongly said: "To even mention that the heavy metals that were listed in his test are in rat poison, leading to articles suggesting Brittany ingested that or anything like it, is absurd. If she had, don't you think it would have shown up in the coroner's test of her blood and tissue?
"A reputable expert will tell you that what this lab did is an ethical violation of the highest order; to even pretend to be able to draw such conclusions on unreliable evidence is the real crime.
"We will never know for sure [why Brittany died]. However, we do know the Los Angeles County Coroner did extensive tests and found that she died of natural causes. And now she is a real living angel in heaven."