Whitney Houston's official cause of death was announced on Thursday by the Los Angeles County Coroner's Office, more than a month after the 48-year-old singer was found dead in a bathtub at the Beverly Hilton Hotel on Feb. 11. The L.A. County coroner stated that Houston died of accidental drowning, with contributing factors of atherosclerotic heart disease and cocaine in her system.

ABC News reported: Ed Winter, spokesman for the Los Angeles cororner's office, told ABCNews.com that the singer's cause of death was drowning aggravated by a pre-existing heart condition called atherosclerotic heart disease. Cocaine was also found in her system, but the coroner's office refused to comment on how much of the drug was found during the toxicology testing. But in the official report under the category 'HOW INJURY OCCURRED' it is noted that the singer was 'found submerged in bathtub filled with water; cocaine intake.'

Other drugs found in her system included marijuana, Xanax, the muscle relaxant Flexeril and Benadryl. These drugs did not contribute to her death.

L.A. Country Chief Coroner Craig Harvey said that Houston had a 60 percent narrowing of her arteries which suggest a cardiac event complicated by the cocaine use that led to her slipping underwater in the bathtub, according to the L.A. Times.

One of the most troubling aspects of the autopsy was the toxicology report, which suggested chronic usage of drugs. Friends and family had said that Whitney Houston was sober before her untimely death.

A friend of Houston's family told HollywoodLife.com that Houston's mother is truly distraught over the news. Cissy is beside herself with grief. She's devastated by the news that cocaine was found in Whitney's system. She was under the impression that Whitney had stopped using the drug. Adding, She always felt that if anything tragic were to happen to Whitney it would be because of cocaine.

TMZ reported on Friday that Whitney Houston, who had been filming Sparkle and working towards a professional comeback, fell prey to cocaine once again as the Grammys inched closer.

Whitney Houston battled drug use for over a decade before she died. Many blamed ex-husband Bobby Brown for her downfall. Here is a timeline of her struggle with substance abuse. 

July 18, 1992: Whitney Houston Marries Bobby Brown

Whitney Houston married R&B star Bobby Brown. Bobby Brown met Whitney Houston, a rising star from Newark, NJ, at the 1989 Soul Train Music Awards. Houston tried to get Brown's attention by throwing things at his head. Apparently, the schoolgirl flirting worked; the couple married on July 18, 1992, after three years of dating. One year later, Houston gave birth to their daughter Bobbi Kristina. This was one of Houston's most professionally successful years. She starred alongside Kevin Costner in The Bodyguard and also recorded the film's soundtrack, which included I Will Always Love You. This soundtrack would win Houston a Grammy for Best Album.

Late-1990s: The Downfall Begins  

Though Whitney Houston said that she was very much in love and happy in a 1992 interview with NBC, the late 1990s brought rumors of drug abuse and personal turmoil. Houston's persona shifted from the good girl she was in the late-1980s and early-1990s. She began showing up late for interviews, photo shoots and rehearsals. She was even known to cancel appearances at the last minute. Rumors of drug use with then-husband Bobby Brown began to circulate.

January 11, 2000: Drugs Found at Airport

On January 11, 2000, security at an airport in Hawaii found marijuana in both Houston's and Brown's luggage. The couple boarded the plane and departed before authorities could arrive. The charges against them were dropped.

2001: Weight Loss

Whitney Houston attracted attention for her noticeable weight loss this year. Her dramatically different physical appearance further spawned rumors of drug and alcohol abuse, but the rumors were quickly squashed by her publicist, who said she had lost weight as a result of stress due to family matters, according to MTV. When she is stressed she doesn't eat, her publicist said in a statement.

2002: Interview with Diane Sawyer

In a 2002 interview with journalist Diane Sawyer for Primetime, Whitney Houston discussed the drug use. First of all, let's get one thing straight. Crack is cheap. I make too much money to ever smoke crack. Let's get that straight. Okay? We don't do crack. We don't do that. Crack is wack, she said. This quote from Houston became headline fodder in later days. 

Sawyer asked Houston if she thought of herself as addicted. Houston responded: I don't like to think of myself addicted, I think of it as having a bad habit. Houston explained how she did not party in her early twenties and ultimately released her inner rebel as she grew older. Houston denied smoking crack, but said she experimented with alcohol, marijuana, cocaine and pills.

2003: Domestic Abuse

In 2003, Bobby Brown was charged with misdemeanor battery after he allegedly hit the singer after a heated fight. Despite these domestic abuse charges, the couple stayed together.

2004: Rehab

Whitney Houston checked herself into a rehabilitation center in 2004. Within a week, she checked out.

2005: Being Bobby Brown, Back to Rehab

In 2005, Whitney Houston and then-husband Bobby Brown appeared on their own Bravo reality show, Being Bobby Brown. The show revealed a train wreck-lifestyle. It highlighted the sheer dysfunction of the family unit; Houston herself admitted that. Reviews lambasted the couple. The Hollywood Reporter declared it undoubtedly the most disgusting and execrable series ever to ooze its way onto television. The public began to seriously worry. Houston returned to rehab again this year.

October, 18 2006: Divorce

In 2006, Whitney Houston filed for divorce from Bobby Brown in Southern California's Orange County Superior Court. Houston asked for custody of daughter Bobbi Kristina, who was 13-years-old at the time. They fought like cats and dogs. They would fight about what to eat for dinner, about who wasn't cleaning out the dishwasher. Stupid things. But they were always yelling, People magazine reported at the time.

2008: Bobby Brown's Autobiography

After his tumultuous relationship and a very public divorce, Bobby Brown released an autobiography to defend himself against rumors that he sullied the reputation and the lifestyle of superstar Whitney Houston. In the 2008 autobiography Bobby Brown: The Truth, the Whole Truth and Nothing But..., Brown gave his side of the story.

What people fail to realize is that Whitney is no punk. She definitely knows how to handle and defend herself in situations that could have potentially been violent. Some of the stories in the media made me out to be like Ike Turner, when that wasn't my character. He also said that it was Whitney who was the bad influence and introduced him to hard drugs. I never used cocaine until after I met Whitney. Before then, I had experimented with other drugs, but marijuana was my drug of choice.

2009: Interview with Oprah Winfrey

Whitney Houston's most famous interview took place in 2009 with talk show host Oprah Winfrey. During this very candid interview, Houston discussed her drug use as well as her suffocating relationship with Brown. Houston admitted that she began experimenting with drugs before the release of The Bodyguard but that the habit became more severe afterwards.

Houston discussed how drugs tied into her troubled marriage. She said that she and Brown would smoke marijuana laced with cocaine. They would sit next to each other for days, hardly speaking, because they were both so stoned. We weren't buying, like, $20 jumbos; we were paying money, we were buying, like, an ounce...We weren't doing, like, pipe smoking, we didn't get that far. You put your marijuana, you lace it (with cocaine), you roll it up and you smoke it in your weed...It's almost like heroin and cocaine speed-balling, but you level it off with the marijuana, she said.

I was losing me into [the marriage], she said. by trying to be pleasing. She said that she did not do things by herself; she did everything with him. I was so weak to him. I was so weak to the love, she said. He was my drug. I didn't do anything without him. I wasn't getting high by myself. It was me and him, together. We were partners. 

2010: An Attempt at a Comeback

Whitney Houston attempted to make a professional comeback in 2010, but it was obvious that drug use had taken its toll. She was criticized by fans for having a croaky voice and seeming disorientated during her performances, according to the Daily Mail. On opening night of her comeback tour, audience members said she appeared exhausted after just one performance. She even took a 20-minute break to catch her breath in the middle of the show, according to reports.

May 2011: Back to Rehab

The superstar singer enrolled herself in a rehabilitation center for the third time in 2011. The prior stints, in 2004 and 2005, did help to quell her drug and alcohol abuse. She was enrolled as an out-patient and cited drug and alcohol problems as her reason for enrollment. A representative for Houston at the time said that it was a part of Houston's longstanding recovery process.

February 11, 2012: Whitney Houston Found Dead

On February 11, 2012, Whitney Houston was found dead in the bathtub of Suite 434 at the Beverly Hilton Hotel just hours before Clive Davis' pre-Grammy party. Paramedics arrived at 3:30 p.m. and attempted to revive the singer to no avail. She was pronounced dead at 3:55 p.m. The Los Angeles County Coroner revealed Houston's cause of death as accidental drowning with contributing factors of the effects of atherosclerotic heart disease and cocaine use.