In California, unless a physician is present at the time, a death is ALWAYS treated as a murder. This insures that the scene is treated as a crime scene and potential evidence isn't destroyed. As soon as an autopsy verifies a cause of thead, the staus will be updated.
Usually it turns out not to be murder.
Apparently the autopsy agreed with the cops that it is a homicide. They must know the cause of death in order to say that.