L'Wren Scott committed suicide, an autopsy conducted by the New York City medical examiner's office determined on Wednesday.
Scott, 49, was found dead after hanging herself with a scarf and a tie in her New York City apartment on Monday morning.
The fashion designer texted her assistant to come over 90 minutes before her body was discovered.
According to longtime friend and former New York Times fashion critic Cathy Horyn, L'Wren was set to announce her business closure this week.
"I learned since her death that she was planning to close her business, with an announcement, on Wednesday," Horyn wrote in a piece for the New York Times on Tuesday. "Still, as painful as the decision must have been for her, I wouldn't draw any conclusions from it about her state of mind."
Scott was reportedly $6 million in debt.
"Like many small designers, she had problems managing her business," Horyn continued, recalling a time two years ago when she urged L'Wren to slow down. "I told her she should give herself time to resolve matters or get out. Putting her health in jeopardy because of stress was not worth it, I told her. She didn’t like the advice."
Although their friendship was tested, Scott reached out to Horyn in early February.
"When we finally spoke… I was surprised to hear how run down and discouraged she sounded," she recalled. "She spoke of production problems, forcing her to cancel her fall show. Again, I urged her to put her health first."
Horyn notes that friends of L'Wren's — who saw her on Sunday night — were "deeply concerned," but never thought she would "do something so desperate."
"Still, as painful as the decision must have been for her, I wouldn’t draw any conclusions from it about her state of mind," Horyn said. "Nor should any credence be given to reports of a breakup with Mick. It’s rubbish.”
Mick Jagger, 70, had been dating the celebrated fashion designer since 2001.
"I am still struggling to understand how my lover and best friend could end her life in this tragic way," the Rolling Stones frontman wrote in an emotional tribute on Tuesday. "We spent many wonderful years together and had made a great life for ourselves. She had great presence and her talent was much admired, not least by me. I have been touched by the tributes that people have paid to her, and also the personal messages of support that I have received. I will never forget her."
The Rolling Stones have since canceled their Australia and New Zealand tour dates; however, the band is rallying to support Mick.
“No-one saw this coming," Keith Richards said in a statement. "Mick’s always been my soul brother and we love him. We’re thick as thieves and we’re all feeling for the man. We really hate to disappoint our fans but we’ll see everyone really soon.”
Guitarist Ronnie Wood also offered his condolences: "This is such terrible news, and right now the important thing is that we are all pulling together to offer Mick our support and help him through this sad time. Without a doubt we intend to be back out on that stage as soon as we can."
"Needless to say we are all completely shocked, but our first thought is to support Mick at this awful time," added drummer Charlie Watts. "We intend to come back to Australia and New Zealand as soon as it proves possible."
A date for Scott's memorial service has not been released at this time.