Credit: Michael Bezjian/

The Dec. 20 death of Brittany Murphy remains a mystery.

On Wednesday, L.A. coroners revisited the Hollywood Hills home where Murphy died at age 32, and told a TMZ video crew that "the investigation" of her death "is continuing."

The actress' official cause of death has still not been released, pending the results of toxicology and histiological reports. Murphy's husband Simon Monjack and her mother Sharon Murphy -- who tried in vain to revive the star on her final morning -- have insisted that Brittany died of natural causes. In sometimes bizarre joint interviews, both have dismissed talk that Murphy abused prescription drugs and suffered from an eating disorder.

Assistant Chief Coroner Ed Winter told TMZ that "the family has been very cooperative" and "we were able to fill in some questions involving the case."

Citing sources, TMZ claims that the pathologists plan to interrogate Monjack and Sharon Murphy further; there are reportedly no records of the actress visiting a doctor in her final months, despite her severe medical problems.

On Wednesday, Monjack abruptly cancelled an event celebrating his late wife and a new "Brittany Murphy Foundation." He had suggested that attendees pay $1000 to attend, with proceeds going to the new charity. Monjack told guests that he had come down with pneumonia.

But a source told, "He probably realized that everyone thought what he was doing was so tacky, so he decided to cancel."