Beverly Hills police said Monday they had completed their preliminary investigation into the death of Whitney Houston and have turned the case over to the Los Angeles County Coroner's Office. 

Authorities are awaiting the results of toxicology tests before an official cause of death can be determined. 

Police Lt. Mark Rosen confirmed today that the fallen star was found unconscious and unresponsive in the bathtub of her Beverly Hilton hotel room Saturday afternoon by a member of her personal staff. Beyond that, he said, police would provide no further information while the coroner's office conducts its investigation.   

Rosen also said during a press conference that tapes of the 911 call won't be released until the investigation has been concluded, which could take six to eight weeks. 

Assistant Chief Coroner Ed Winter, who also spoke with reporters today, said prescription medications were found in Houston's hotel room, but only in small quantities normally seen in a medicine cabinet. While authorities say they're not ruling out any cause of death pending toxicology results, they have said there were no signs of foul play. 

Tags: Whitney Houston