Officials are still waiting for the results of toxicology tests before determining the cause of Houston's death Feb. 11, the Los Angeles Times reported.
Police in Beverly Hills, Calif., have said they don't suspect foul play, but law enforcement sources told the Times the investigation into the recording star's death remains active.
The insiders also said it could be a few more weeks before an official cause of death is announced.
Houston, who had battled addictions to drugs and alcohol for years, was found dead in the bathtub of her room in the Beverly Hilton hotel a day before the Grammy Awards, which she was slated to attend. She was 48.