Whitney Houston's autopsy complete, toxicology reports awaited

As mystery surrounds the sudden death of singer Whitney Houston, the authorities have completed an autopsy but results were withheld pending toxicology report that will determine the cause of her death.

The toxicology report may take six to eight weeks.

Authorities have already ruled out foul play in Houston's death. The 48-year-old singer's body was found by a member of her entourage on Sunday.

An autopsy began on Sunday but results would be withheld at the request of Beverly Hills police, said Captain John Kades of the Los Angeles County coroner's office.

Coroner Ed Winter said Houston was found in the bathtub of her Beverly Hilton Hotel room in California. He declined to say whether she drowned.

According to US reports, the autopsy revealed that the singer did have water in her lungs when she died.

It is believed that Houston, who had a history of drug addiction, may have fallen asleep or lapsed in unconsciousness in the bathtub and drowned.

The medical examiner needs to determine whether Houston died before she was submerged in the water or after. There is also a possibility that she was dead before she went under the water, TMZ reported quoting law enforcement sources.

Houston died a day before Grammy awards where she was to appear. The awards went without Houston but music bigwigs took to stage to pay rich tributes to her musical accomplishments.

Houston, a pop sensation in the 1980s and one of the best-selling artist, battled alcohol and drug addiction.

She had returned to her hotel after attending a rehearsal party for a pre-Grammy party hosted by music mogul Clive Davis.