(CNN) -- L'Wren Scott, a noted fashion designer who has been Mick Jagger's companion for more than a decade, was found dead in her New York apartment Monday of an apparent suicide, according to a law enforcement official familiar with the investigation. She was 49.

Scott's assistant found the designer hanging from a door knob with a scarf around her neck, the official said.

There were no signs of forced entry, and police did not find a suicide note, the official said.

Her assistant told police Scott sent a text Monday morning asking the assistant to "come by, and when the assistant arrived at approximately 10:02 a.m., Scott was dead in the living room, prompting the assistant to call police," according to the official.

The New York Medical Examiner will determine the cause of death, according to Sgt. Nieves with the New York Police Department

A spokesman for Mick Jagger said that the singer was completely shocked and devastated by the news.

Scott had been dating Jagger, 70, since at least 2003. The lanky former model designed clothes worn by a number of celebrities, including Madonna, Allison Williams and Christina Hendricks. She also created many of Jagger's looks for the Rolling Stones' 50th anniversary tour, which began in 2012 and is currently in Australia.

The band called off Wednesday night's show in Perth, following the news.

"Frontier Touring and Concerts West regret to announce that The Rolling Stones concert in Perth will not be going ahead as scheduled for Wednesday 19 March 2014," a statement on the Perth Arena website said. Ticket holders were told to hold on to their tickets for the show.

In addition to her haute creations, she designed a collection for Banana Republic that was introduced late last year.

"I don't really jump on anything unless I believe it will deliver the quality and standards I stay true to. It is a very fun happy collection and I think it is classic and timeless and elegant," she told Vanity Fair at the introduction last October.

Celebrities attending the event included Hendricks, Ke$ha, Rashida Jones and Michael B. Jordan, as well as Jagger.

On Monday, several stars mourned Scott on social media.

Actress Olivia Munn tweeted, "Shocked and saddened by the passing of @lwrenscott ... she was an amazing soul, talented artist and an unbelievably giving friend. RIP." Fellow designer Rachel Roy tweeted, "Rest in Peace, L'Wren Scott. You will be forever missed."

Mick Jagger's first wife, Bianca Jagger, tweeted, "Heartbroken to learn of the loss of the lovely and talented L'Wren Scott. My thoughts and prayers are with her family. May she rest in peace." Singer and actress Bette Midler tweeted, "Just got news of the beautiful L'wren Scott's death perhaps by her own hand. I am devastated. A rare, wonderful, talented soul. Goodbye."

Cosmetics maven Bobbi Brown released a statement saying "I'm devastated by the tragic news about L'Wren. She was an incredible designer who I considered my friend. My heartfelt condolences go out to her loved ones during this very sad time."

Scott was born Laura "Luann" Bambrough and raised in Utah. The statuesque beauty -- she was 6-foot-4 -- was first spotted by photographer Bruce Weber at a Calvin Klein hosiery shoot, according to Vogue.

After modeling for several years, she became a stylist and eventually designed costumes for films such as the 1996 remake of "Diabolique" and 2000's "Mercy." She also received a credit on 2007's "Ocean's Thirteen" as actress Ellen Barkin's consultant.

People we lost in 2014

CNN's Shimon Prokupecz and Elizabeth Landers contributed to this report.