Late actress Brittany Murphy's mother-in-law has joined forces with the tragic star's father in calling for a new investigation into her death.

A Los Angeles coroner ruled that Murphy's December, 2009 death was the result of pneumonia, anaemia and excessive use of prescription medications, but her father, Angelo Bertolotti, was far from satisfied with the results, and in 2012 he filed suit against the Los Angeles Police Department and the Los Angeles Coroner's Office, asking officials to re-open the investigation.

He also conducted his own private tests on the Clueless star's hair and tissue samples, and recently revealed her body contained abnormally high levels of several metals, insisting that his findings suggested his daughter had been poisoned by "a third party perpetrator with likely criminal intent."

Murphy's mother-in-law, Linda Monjack, also believes there could have been foul play involved in the death of her daughter-in-law and son, Simon, who passed away from pneumonia just five months after Murphy's death.

She tells U.S. breakfast show Good Morning America, "They had everything to live for and it was snatched away from them. I do think something is extremely wrong, it doesn't feel right, it doesn't sit right."

Monjack feels the similar circumstances surrounding the deaths of her son and his wife should have raised a red flag.

She continues, "That to me would have been alarm bells, but nobody seemed to take that up."

Investigators at the Los Angeles District Attorney's office are not willing to re-open an investigation, but officials at the Los Angeles Coroner's office have agreed to take a look at the results from the independent inquiry after they receive them.

She continues, "I just hope that it comes to something in the end and justice is served."