A plane owned by actor-producer Tyler Perry landed at an airport in Teterboro, New Jersey, where security was tight. A gold hearse left the airport and arrived just before midnight at the Whigham funeral home in Newark, the city where Houston was born. A crowd of about 50 fans had gathered outside.

A spokeswoman for Houston's family said plans for a memorial had not yet been completed, but media reports have said a public viewing and funeral would be held later this week.

Houston, 48, rose from singing in a church choir to become one of the best-selling and most admired performers of her generation.

She won six Grammys and more than 400 other awards in a 25-year career that also saw her star in such blockbuster films as "The Bodyguard." She was best known for her 1992 hit single "I Will Always Love You."

But Houston's success was eclipsed later in life by problems with drinking and drugs. She had a long history of addiction to alcohol, cocaine and marijuana, admitting so on television talk shows. She was in rehab as recently as May 2011.

Houston died in a Beverly Hills hotel room Saturday on the eve of the music industry's Grammy Awards, and because of her drug battles, speculation arose that she might have died of a drug overdose.

On Monday, Beverly Hills police called a news conference to address the media "rumors," but did not add much additional information. They did say the singer's body had been found underwater in the hotel room's bathtub.

"Ms. Houston was apparently discovered in the bathtub by a member of her personal staff," who called hotel security, Beverly Hills Police Lieutenant Mark Rosen said. She was pulled from the bathtub, but when paramedics arrived "she was unconscious and unresponsive," he said.

CAUSE OF DEATH STILL UNKNOWN

Rosen declined comment on whether prescription drugs were in the room or the condition of Houston's body. Detectives have sealed their inquiry, he said.

"We are not conducting a homicide investigation at this time. We do not know the cause of death, we do not know the circumstances leading up to her death," Rosen said.

An autopsy was completed on Sunday, and a final death report is pending completion of an official investigation and toxicology reports that may take weeks to finalize.

Los Angeles assistant chief coroner Ed Winter said prescription medication was found in Houston's room, but he declined to detail the names of the drugs or the amount found.

Dr. Andrew Baker, president of the National Association of Medical Examiners who is not involved in the probe, told Reuters autopsies were good at establishing or ruling out death from causes like trauma, heart disease or aneurysm.

"The autopsy is going to rule out 95 percent of things," he said. "But when it comes to diagnosing any kind of poisoning or intoxication or overdose, it really does come down to lab tests."

Meanwhile, Houston's brother-in-law, Billy Watson, told ABCNews.com on Monday that he doesn't believe the singer would have taken her own life.

"Oh, no, this is accidental," he said. "She wouldn't have left her daughter like that. She wouldn't have done that to her daughter."

Houston's daughter, Bobbi Kristina Brown, 18, was in Los Angeles when her mother died.

Houston had been in Los Angeles for the Grammys and planned to attend an annual pre-award party hosted by record producer Clive Davis on the night she died.

Houston's death prompted a parade of music industry stars to express adoration for her and her rise to the top of the music world. Ex-Beatle Paul McCartney and his wife, Nancy Shevell, on Monday visited a makeshift memorial outside the Beverly Hilton hotel where Houston died, placing yellow roses alongside the numerous other bouquets.

As with the 2009 death of pop superstar Michael Jackson, Internet sales of Houston's songs surged after her death.

On Monday, her album "Whitney Houston - The Greatest Hits" was the top seller in the music category on Amazon.com, and "I Will Always Love You," was the No. 1 download at iTunes, just ahead of Grammy winner Adele's "Rolling in the Deep."

(Additional reporting By Jill Serjeant and Lisa Richwine in Los Angeles and Jonathan Allen in New Jersey; Editing by Bob Tourtellotte and Eric Beech)

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