The singer had struggled for years with cocaine, marijuana, and pills, and her behavior had become erratic.
Houston, 48, was found Saturday at the Beverly Hilton Hotel by a member of her staff about 3:30 p.m., hours before she was to appear at a pre-Grammy Awards gala, police Lt. Mark Rosen said. Members of her staff pulled her from the tub, and hotel security was promptly notified, Rosen said. Houston was pronounced dead about a half-hour later.
"As of right now, it's not a criminal investigation," Rosen said, refusing to release further details. "We have concluded our portion of the investigation at the hotel."
Los Angeles County coroner's assistant chief Ed Winter said there were bottles of prescription medicine in the room. He would not give details, except to say: "There weren't a lot of prescription bottles. You probably have just as many prescription bottles in your medicine cabinet."
The coroner's office released the body to the family Monday morning. Later, a police convoy accompanied two vehicles into a Van Nuys Airport hangar, and a private jet rolled out of the hangar and took off in midafternoon.
Two people who spoke with Houston's family said the singer would be taken to New Jersey. The two, who spoke on condition of anonymity because they weren't authorized to speak for the family, said Houston's relatives raised the possibility of a wake Thursday and funeral Friday at Newark's Prudential Center, which can seat about 18,000 people.
Houston was born in Newark and raised in nearby East Orange. She began singing as a child at Newark's New Hope Baptist Church, where her mother, Grammy-winning gospel singer Cissy Houston, led the music program for many years.
The White House said President Obama's thoughts and prayers were with Houston's family, especially her daughter. White House press secretary Jay Carney paid tribute to the singer's "immense talent" and said it was a tragedy to lose somebody so gifted at such a young age.
Houston's death tinged the Grammy ceremonies with sadness. It also probably boosted viewership, which was 50 percent higher than last year, with nearly 40 million viewers tuning in to the program on CBS.
A sensation from her first album, Houston was one of the world's best-selling artists from the mid-1980s to the late 1990s. But as she struggled with drugs, her majestic voice became raspy, and she couldn't hit the high notes.
Mourners left flowers, balloons, and candles at the wrought-iron fence around the tall brick Newark church where Houston got her start.
"She was an inspiration to everybody," said Gregory Hanks, an actor who grew up in the neighborhood and who dropped off a bouquet. He saw Houston perform in New Jersey years ago.
"I grew up listening to her as a little boy, and to hear her sing, you knew she was special," he said.