Whitney Houston 'accidentally drowned in her bath' Patricia Houston, the singer's sister-in-law and manager, said: "We are saddened to learn of the toxicology results, although we are glad to now have closure." Bottles of prescription medication had been found in the hotel room, but not in large numbers, and those drugs played no part in the singer's death. No cocaine was found in the hotel room. The official cause of death was given as "drowning and effects of atherosclerotic heart disease and cocaine use." The coroner's office said the death was an "accident." According to the toxicology report: "Cocaine and metabolites were identified and were contributory to the death. Marijuana, Alprazolam (Xanax), Cyclobenzaprine (Flexeril) and Diphenhydramine (Benadryl) were identified but did not contribute to the death. A source close to the investigation told celebrity news website TMZ it was "very possible" the singer had a heart attack that resulted in her becoming unconscious and drowning. A heart attack could have been caused by hardening of the arteries resulting from use of cocaine, TMZ reported. The singer was buried in a New Jersey cemetery next to her father after an emotional four-hour funeral service that was attended by friends, family and stars including Oprah Winfrey, Alicia Keys and Mariah Carey. Houston, a sensation from her first album in 1985, was one of the world's best-selling artists from the mid-1980s to the late 1990s, with hits including "I Wanna Dance With Somebody," "How Will I Know," "The Greatest Love of All" and "I Will Always Love You." But as she struggled with drugs her voice became raspy and she could no longer hit the high notes. Interest in her music has increased dramatically since her death, pushing her songs back in to charts and radio playlists.