Nearly four years after Brittany Murphy's death, the father of the Hollywood starlet has challenged the official cause amid speculation that the actress could have been poisoned.

Murphy died in December 2009 at the age of 32. The Los Angeles Coroner's Office ruled her death accidental and attributed it to natural causes. The office cited pneumonia, noting that Murphy's condition was compounded by severe anemia and prescription medication in her system.

The actress, a performer since childhood, was best known for performances in films such as Clueless, Eight Mile and Girl, Interrupted as well as voice roles on TV's King of the Hill and the animated movie Happy Feet.

Her husband, 40-year-old screenwriter Simon Monjack, was found dead just five months later. His cause of death was also ruled to be pneumonia compounded by anemia.

In 2012, Murphy's father, Angelo Bertolotti, filed a lawsuit against the Los Angeles Coroner’s Office and the Los Angeles Police Department. He accused authorities of incorrectly determining his daughter's cause of death and sought further toxicology testing. The lawsuit was dismissed.

Brittany Murphy and Simon Monjack

Screenwriter Simon Monjack was found dead just five months after his wife Brittany Murphy's death. (David Livingston/Getty Images)

Bertolotti, who had been estranged from Murphy and her mother Sharon, claims he was able to obtain tissue samples and that analysis by Colorado-based independent testing facility Carlson Company revealed an abnormal presence of 10 heavy metals and toxins in the samples.

He has called on authorities to re-open the investigations into Murphy and Monjack's deaths, but the coroner's office declined.

In statements to media, the office said it had no plans to re-open the two cases and stands by its original findings. Officials said they have not received any private lab results and hence could not comment on them.