News of Whitney Houston's sudden death rocked the music industry and millions of fans worldwide, after the 48-year-old pop star was found unresponsive in a bathub at the Beverly Hilton Hotel on Saturday, Feb. 11, 2012.

The pioneering solo artist had been preparing to attend a pre-Grammy Awards party hosted by her mentor Clive Davis. Her premature death cast a grim shadow on the Grammy Awards ceremony, which was marked by tributes to the fallen star.

Though the official cause of death has not yet been confirmed, an unnamed law enforcement official told Fox News that drugs and alcohol are likely to blame.

It looks like it was a lethal combination of prescription drugs and alcohol, but it's still too early to rule out other causes. That's just what it's looking like now, the official said.

Houston's 1985 arrival on the music scene was named on USA Today's 2007 list of 25 memorable musical moments of the previous quarter-century. Her incredible vocal range and supermodel looks earned her virtually instant stardom after Davis discovered the 19-year-old singing with her mother Cissy's cabaret act.

Her debut album Whitney Houston remains one of the best-selling solo album of any female artist in music history, and the pop superstar is credited with breaking down racial barriers in the entertainment industry: She was the first African-American female performer to be given heavy rotation on MTV, and later played the female lead alongside Kevin Costner in the interracial romance The Bodyguard.

Houston enjoyed unrivaled success and a squeaky-clean image throughout the 1980s and into the early 1990s, but began to show signs of personal turmoil not long after her eyebrow-raising marriage to R&B star Bobby Brown in 1992. While she continued to record music and began a commercially successful string of film roles, over the years Houston appeared unhinged from drug use and a volatile marriage.

Though many were dubious of Houston's oft-quoted claim that she did not use crack cocaine, the troubled star often acknowledged her struggles -- even if she didn't always call them by name.

It is a wonderful, marvelous feeling to be looked at and not judged, she said in her 2010 BET Honors acceptance speech, prompting an eruption of applause.

I want us to be proud of each other, she continued. With grace, with mercy, with integrity and dignity for each other. Let's continue to lift each other up; not only in our triumphs, but when we're going through our trials and our tribulations.

Earlier in the ceremony, Houston stood in the front row and cheered Jennifer Hudson on as she performed I Will Always Love You, the song Houston made famous -- and one that Hudson would perform again at the 2012 Grammy Awards the day after the superstar's death.

'Love is where you find it'

Houston's 2002 interview with Diane Sawyer on Primetime appears to have been intended to set the record straight on her marriage and her drug use, but instead amplified concerns about her physical and mental health.

 It wasn't always about the drug, a raspy-voiced Houston told Sawyer. I would stay in my room for days at times, just trying to get it together to know what my next phase was going to be.

Houston spoke of her time working on The Bodyguard with Costner, explaining that she felt so overwhelmed by the pressure to deliver a performance worthy of her co-star that she told her husband she needed to quit.

He said, 'No way are you going to do that. If you quit now, you're going to blame me for the rest of my life. You're going to do this movie, and you're going to do it well.

While the film itself was largely dismissed by critics, the soundtrack -- propelled by Houston's searing performance of Dolly Parton's ballad I Will Always Love You -- cemented the pop star's legendary status. The album is the best-selling soundtrack of all time, and currently holds the record for the longest run at the top of the charts (though Adele's 21 is perched to overtake it).

At the time of the interview, Bobby and Whitney had been married for 10 years, enduring two separations and scads of bad press along the way.

Questioned by Sawyer about the unlikely pairing, Houston was defiant in defense of her marriage.

Love is where you find it, Houston said. And I found it in him, and he found it in me.

Though she denied having ever been physically abused by Brown, Houston admitted she had hit him in anger at times.

When Sawyer suggested that Brown was controlling, and their abusive marriage was a magnet that kept pulling Houston back, the singer defended her husband.

The magnet that you're talking about is my love, and my protection for him, Houston insisted. She then admitted there was a time in her marriage when Sawyer's characterization might have been accurate, but claimed the trouble was behind her.

I'm older and I'm wiser now, she said. It's not the Svengali tactic anymore.

'I was losing me'

In a 2009 interview with Oprah Winfrey, after she and Brown had divorced, Houston was more forthcoming about the marriage, admitting that her ex-husband's substance abuse problems contributed to her own struggles with drugs. While she maintained her earlier claim that Brown was never physically abusive towards her (though she later described instances where he slapped and pushed her), she characterized his verbal abuse as horrifying.

During the interview, Houston was visibly distressed when Oprah read aloud from a Los Angeles Times review of her 2009 album, I Look to You.

The pain, and frankly, disgust that so many fans felt during Houston's decline was caused not so much by her personal distress as by her seemingly careless treatment of the national treasure that happened to reside within her, Oprah read from the article.

When I became 'Whitney Houston' and all this other stuff happened, my life became the world's, Houston explained. My privacy, my business...and I was like, 'that's not fair.'

I wanted to go to the park. I wanted to walk down the street with my husband, hand in hand, she continued.

It was just too much. Too much to try to live up to, to try to be...I wanted out at some point.

Was marrying Bobby a way to be out? Oprah asked her.

In a sense, Houston said. Because he allowed me to be me.

When asked if Bobby was jealous of her, Houston paused before answering.

He's not going to like this, but yes.

Houston claimed the she agreed to participate in the reality show Being Bobby Brown in order to let people know that I was his wife. But she admitted that she wasn't happy with her marriage, or herself, at the time.

A lot of people after...seeing you on that show started to really worry about you and what was really going on with you, Oprah said. What was going on with you at that time?

There were a few things, Houston said. I was losing me, into that.

Into the marriage? Oprah asked.

Yeah. By trying to be pleasing.

'He was my drug'

Whitney pointed to The Bodyguard as the turning point in her life on a number of levels, acknowledging that she used drugs before the film, but said after 'The Bodyguard' started getting heavy. Houston said her drugs of choice were cocaine and marijuana, and that by the time she filmed The Preacher's Wife in 1996, she was using every day.

When it gets to the point when you're sitting in your home and you're just trying to cover what you don't want people to's painful, she told Oprah. And then you want more, just so that you don't let anybody see you cry, or let anybody see that it's not working, that you're not happy.

[Bobby] was my drug, she said later in the interview. I didn't do anything without him. I wasn't getting high by myself. It was me and him, together...We were partners. And that's what my high was: Him.

Indeed, an unhealthy personal relationship is known to compound addiction problems for those with a propensity toward substance abuse.

A volatile relationship can serve as a trigger, especially if they argue a lot or if there is a tumultuous relationship, addiction specialist Dr. Harris Stratyner, the regional clinical Vice President of Caron Treatment Center, told Fox News. Addicted individuals look for reasons to use. So, if they fight a lot or disagree the addicted individual is going to go out and use.

Many of Whitney's fans will always associate her decline with her marriage to Bobby Brown.

I think that if you look at the arc of Whitney's career the problems definitely seemed to creep into her music career and her personal life when she got together with Bobby Brown, editor M. Tye Colmer told Fox News. If you look at those moments there is definitely a connection that turned out to be very self-destructive. Even after she and Bobby divorced, she was never able to escape the problems she faced with Bobby.

Houston's struggles with substance abuse continued well after her marriage ended in 2007. She had been in and out of rehab multiple times, most recently in May 2011 -- not long after she appeared at a number of Prince concerts visibly intoxicated. Houston's reportedly erratic behavior prompted Prince's handlers to ban her from any future performances.

'I've got some good saints'

Houston looked and sounded well in what is believed to be her final official interview in Nov. 2011 with Access Hollywood, from the set of her upcoming film, Sparkle.

There'll be the up and there'll be the downs, Whitney told Shaun Robinson.And then there'll be the all-arounds.

Robinson relayed a message from someone who wanted Houston to know how many people were rooting for her, and then asked if the singer could feel the support that she has.

I've got some good saints out there, Houston said. That pray for me constantly. You gotta have that.

I'm older, I've matured, she later continued. I'm looking forward to the years as they come.

Whitney appeared to have experienced a setback in the days preceding her sudden death. Rumored to be flat broke and staying in Beverly Hills on her record label's dime, Houston got into a verbal altercation with a romantic rival at a pre-Grammy party Thursday night, after joining Kelly Price onstage for an impromptu performance. Whitney appeared disheveled and sweaty as she was photographed leaving the party, and was reportedly bleeding from a cut on her leg.

Houston was seen at the Beverly Hilton Friday night, drinking and chatting loudly with friends. According to a recent article in Time magazine, drug addicts are at a particularly high risk of overdose following a period of abstinence. If Houston had indeed been clean in the months leading to her death, she may have underestimated her ability to tolerate the prescription pills reportedly found in her hotel room  -- especially if she was drinking, which is likely to have lowered her inhibitions.

Members of Houston's family who spoke to her on Saturday said she sounded fine. Her brother-in-law Billy Watson told ABC News that many believed Houston was truly on the road to recovery.

We were all feeling she was on her way back, he said. She had a few stumbling blocks in the way, but she was on her way back.