US officials have said it is too soon to determine whether prescription drugs were involved in Whitney Houston's death.
Website TMZ reported that the star's family were told by Los Angeles County Coroner officials that prescription medication mixed with alcohol - and not drowning - appear to be to blame.
But Assistant Chief Coroner Ed Winter said that it was too early to determine what caused the 48-year-old singer to be discovered dead in her bathtub in her room at the Beverly Hilton Hotel.
Asked about the reports, said to have come from family sources, he said: "I'm the one that talked to the family and I did not provide that information..."
He confirmed Houston was found in the bath, but said that it was too soon to determine the cause of death before the results of toxicology tests.
"We are awaiting the results of toxicology tests," he said: "We do not know yet (the cause of death)."
"When we find out ... we will be in contact with the family and give them our findings."
Mr Winter said Houston's family are "making arrangements" to have the singer's body returned to them following the completion of the autopsy.
He said in a press conference: "I don't know when the family is going to have her body. They are making arrangements. Sometimes it takes a couple of days."
He added: "The autopsy has been completed, there is no hold on the body."
The US singer was found by a member of her entourage in her hotel room on Saturday, just hours before she was supposed to appear at a pre-Grammy gala.
Beverly Hills Police Lieutenant Mark Rosen said there were no indications of foul play when she was found.
Paramedics' attempts to revive her were unsuccessful and Houston, once the golden girl of the pop world, was pronounced dead shortly before 4pm.
The 54th annual Grammy awards opened with a prayer and standing ovation to the singer, who herself won a clutch of six prestigious Recording Academy gongs over a turbulent career marred by spells of drug addiction.
Host LL Cool J said: "There is no way around this. We've had a death in our family so at least for me, the only thing that seems right is to start with a prayer for our fallen sister Whitney Houston."
He declared the night one to "celebrate and remember", and played a clip of Houston performing I Will Always Love You from the 1994 Grammys.
Later in the show, actress and singer Jennifer Hudson performed an emotional tribute, singing a rendition of the late star's biggest hit.
Dressed in black, with only the accompaniment of a piano, she had to fight back tears as she sang the song, ending with the line: "Whitney, we will always love you."
Stevie Wonder said: "To Whitney up in heaven, we all love you."
Houston, one of the world's best-selling artists in the 1980s and 1990s, was due to perform at the annual pre-Grammy party of her long-time mentor, record producer Clive Davis at the Beverly Hilton on Saturday.
Meanwhile, Houston's daughter, Bobbi Kristina Brown, was taken to a Los Angeles hospital by ambulance and later released. A source close to the family said she was treated for stress and anxiety.
The 18-year-old, who is Houston's daughter from her tumultuous marriage to singer Bobby Brown, had accompanied her mother to several pre-Grammy Awards events.
Bobby Brown said in a statement: "At this time, we ask for privacy, especially for my daughter, Bobbi Kristina.
"I appreciate all of the condolences that have been directed towards my family and I at this most difficult time."