By Andrew Blankstein and Abby Sewell

LOS ANGELES — The coroner’s investigation into the death of Whitney Houston came to a close Wednesday with a final autopsy report that described the singer submerged face-down in hot water in the bathtub of her Beverly Hills hotel suite with a unidentified white powdery residue left in a spoon on the bathroom counter.

The report released Wednesday confirmed that the 48-year-old singer drowned in a bathtub, with heart disease and cocaine use listed as contributing factors. It concluded that Houston’s death was accidental.

On a counter in the bathroom, investigators found an ashtray filled with cigarette butts and a "small spoon with a white crystal-like substance in it, and a rolled-up piece of white paper." They also found prescription drug bottles on the counter and a small plastic bag that had been ripped open. In a drawer, they found a portable mirror with more remnants of a white, powdery substance. Coroner’s officials said they did not test the powder, saying that was a job for police. The Beverly Hills Police Department did not release any information about the substance Wednesday.

Houston had battled drug addiction for years, and the report found that she had a perforation in her nose typical of habitual cocaine users. Toxicology test results showed that she had cocaine in her system at the time of death. The coroner’s office also found traces of several other drugs — including marijuana, the anti-anxiety medication Xanax, the muscle relaxant Flexeril as well as Benadryl — in her system.