Brittany Murphy's mom, Sharon, is breaking her silence to slam claims that her daughter was poisoned. Murphy's father, Angelo Bertolotti, recently asked for a new toxicology report four years after the actress' death to try and prove that she didn't die from "natural causes."

The new report found heavy metals in Murphy's hair and claimed that she might have been poisoned by a third party. Bertolotti made claims stating that he believed the actress was being surveillance and was poisoned by "government spooks" after she and her husband, Simon Monjack, gave celebrity backing to a government whistleblower.

Monjack and Murphy died within five months from each other from the same causes. Mystery has always surrounded the "Clueless" star's death but her mother decided to refute claims that her daughter was murdered in an open letter with The Hollywood Reporter.

She said she doesn't believe the actress was poisoned and called Bertolotti's theory a bunch of "lies" and "madness."

"I have chosen to stay out of the limelight since the tragic and sudden death of my wonderful, talented, loving daughter," she said. "I have no choice now 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."

Sharon said she was living with Murphy and her husband in their Hollywood Hills home at the time of their deaths. She also said the new toxicology report Bertolotti requested was a fraud.

"This whole stunt is merely publicity to fuel their aspirations. The time has come for their false statements to be exposed and rebuked," she said.

"The lab Angelo used, if you can call it that, is an Internet site that farmed out the actual testing, and then wrote horrible untrue things under the guise of 'analysis.' It mentioned rat poison as a possible cause and claimed to be able to say that a third party murdered my beloved daughter," she contined. "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."

Sharon admitted that they may never know for sure what exactly killed the actress but said that experts believe it what was toxic mold and the mold was eventually found in her house.

"We will never know for sure," she said. "However, we do know the Los Angeles County Coroner did extensive tests and found that she died of natural causes.