Former Pop Idol contestant and theatre star Darius Campbell Danesh has died at the age of 41, his family has announced.
The singer was found unresponsive in bed in his US apartment on 11 August.
However, his cause of death in Rochester, Minnesota, is not yet known.
"It is with great sadness that we announce the passing of Darius Campbell Danesh," a statement issued by his family read.
"The local police department have confirmed that there were no signs of intent or suspicious circumstances. The cause of his sudden death is unknown at this stage, while medical examinations continue.
"We ask that you kindly respect our wishes for privacy at this time whilst we come to terms with the tragic loss of our son and brother."
Born in Glasgow to a Scottish mother and Iranian father, Campbell Danesh was the eldest of three boys and went to Bearsden Primary School before studying English literature and philosophy at the University of Edinburgh.
He first rose to prominence on the ITV show Popstars in 2001, where he became known for his audition performance of Britney's Baby One More Time.
He later came third on the first series of Pop Idol, which was won by Will Young, and his memorable performances included renditions of Tom Jones's hit It's Not Unusual and Atomic Kitten's Whole Again.
His debut single, Colourblind, was released in July 2002 and went straight to number one.
The Scottish singer-songwriter later had a successful theatre career, appearing in West End shows such as Chicago, in which he played Billy Flynn, Guys And Dolls, Gone With The Wind and Funny Girl.
Campbell Danesh starred opposite Ugly Betty star America Ferrera in the musical set in prohibition-era Chicago.
Speaking about his role as Flynn, the actor had previously said he based his portrayal of the character on his old mentor and Pop Idol judge, Simon Cowell.
"He's the consummate businessman and a wonderful guy and there's a lot of Simon Cowell in Billy Flynn in terms of the way he approaches things and I recognise that in terms of the character," he said.
He credited Cowell with persuading him to take on the role in the first place, saying he was "incredibly grateful" for his the opportunities he had been given and "to be able to call Simon Cowell a friend".
After Pop Idol, he won the first series of ITV's Popstar To Operastar contest in 2010, beating Bernie Nolan of the Nolan Sisters in a close final.
A few months after his win, which featured Welsh singer Katherine Jenkins and Mexican-born tenor Rolando Villazon as judges, he landed his first major opera role in the production of Carmen at London's O2 Arena, playing the principal role of bullfighter Escamillo.
In the same year, Campbell Danesh spoke to Hello! magazine about a car crash in which he broke his neck.
He had been a passenger in a Porsche when it crashed into a wall at 70mph in Spain after skidding on oil.
In 2011 in Santa Barbara, California, he married Canadian actress Natasha Henstridge, known for her role in the sci-fi film Species.
However, the couple were divorced a few years later.
'A true gent with a kind soul and a mischievous twinkle in his eye'
News of his death prompted tributes from figures in music and television, with fellow pop star Michelle Heaton saying her thoughts were with his family.
The Liberty X member, who also competed on Popstars, tweeted: "So sad... thoughts with Darius family right now, always our Britney."
English-born actor Matthew Marsden described the news as "truly heartbreaking".
He added: "I first met Darius when he auditioned for the Big Breakfast weather many years ago. He was a terrific human being. My thoughts and prayers go out to his family."
TV and radio presenter Nicki Chapman, who starred as a judge on Popstars while Campbell Danesh was a contestant, described him as a true gent with a kind soul and a mischievous twinkle in his eye".
"There will only ever be one Darius Campbell Danesh," she added.
"From that eventful first audition on Popstars to him kindly inviting me to see him perform on the West End stage. Thoughts are with his family at this sad time."
After both of his parents were diagnosed with cancer and recovered, Campbell Danesh became a supporter of several charities, including Cancer Research UK.