When Brittany Murphy died in 2009 at age 32, a coroner’s report attributed her death to natural causes, while her mother and husband Simon Monjack (who died several months later) begged to differ.

Yet her father, who has launched his own investigation, believes she died of possible poisoning by “a third party perpetrator with likely criminal intent,” Radar Online reports.

According to the official account, Murphy died of prescription drug toxicity combined with pneumonia and anemia. But a report ordered by Murphy’s dad, Angelo Bertolotti, who sent samples of her hair to a lab, found a “high level” of heavy-metal exposure (no, not Iron Maiden… toxins found in substances such as rat poison and insecticides).

Meanwhile, Bertolotti maintains his daughter was neither anorexic nor a drug junkie, as was reported at the time of her death. He says, “I will not rest until the truth about these tragic events is told. There will be justice for Brittany.”