Los Angeles County Assistant Chief Coroner Ed Winter said Wednesday that toxicology tests that could determine Marie's cause of death take about six weeks.
Winter says her body showed no signs of trauma and no illegal drugs were found in the Pasadena home where she died.
Marie, the singer of hits like "Lovergirl" who was often called the "Ivory Queen of Soul," was found unresponsive by family members in her home on Sunday. She was 54.
Police said in a statement that the death appeared to be from natural causes.