Brittany Murphy's British-born husband died from pneumonia, which also killed his actress wife months earlier according to the Los Angeles coroner's office.
Assistant Chief Coroner Ed Winter says 40-year-old Simon Monjack's heart was slightly enlarged.
The screenwriter also had some prescription medications in his system when he died May 23, but not enough to contribute to his death.
Mr Winter said he did not have the list of medications immediately available but said a full report will be issued in about two weeks.
Murphy, star of films such as Clueless died in December and coroner's officials determined she died of a combination of pneumonia and that anaemia and prescription medications played a role.
Mr Winter says both their deaths were probably preventable.