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The clinic where Joan Rivers stopped breathing is "under investigation", a health official confirmed.
The 81-year-old comedienne died yesterday (4 September ).
Rivers suffered cardiac arrest following a routine operation on her throat at the Yorkville Endoscopy clinic in New York last week and was placed on a life support machine. Earlier this week, she was moved to a private room in intensive care .
The New York medical examiner office "will be investigating the death of Joan Rivers", spokeswoman Julie Bolcer told CNN .
New York State Department of Health representative James O'Hara added that the organisation is "investigating the matter".
Career in pictures Joan RiversShow all 15 1 /15Career in pictures Joan Rivers Career in pictures Joan Rivers Joan Rivers Joan Rivers in the 1960s, at the time she was performing in comedy clubs in New York and honing her skills as a comedienne.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers in 1968, the same year she had a bit-part in 'The Swimmer' starring opposite Burt Lancaster. Rivers started to establish herself as a comedian with appearances on the 'The Tonight Show' and even had a short-lived talk show called 'That Show with Joan Rivers'.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers at the Millrun Playhouse Theater in the Round, Niles, Illinois in 1974. By the Seventies, she had become a firm staple on television comedy shows, including 'The Carol Burnett Show'.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers promoting her directorial debut 'Rabbit Test' in 1978. The comedy starred Billy Crystal and told the story of the world's first pregnant man. Rivers even made a brief cameo as a nurse in it. 'Rabbit Test' is the only film Rivers has directed to have received theatrical release in cinemas.
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Career in pictures Joan Rivers Joan Rivers Comedian and actress Joan Rivers in the 1980s, by this point in her career she was focusing on writing. She was a guest contributor on an episode of 'Saturday Night Live' and a regular writer on 'The Late Show'.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers in 1984, the following year she served as writing supervisor on the screenplay for the TV movie 'Joan Rivers and Friends Salute Heidi Abromowitz'. Her popularity was cemented in 1989 when she hosted 'The Joan Rivers Show'.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers in the TV film 'How To Murder A Millionaire' in 1990, in which she played the millionaire of the title. Media historian Hal Erickson reviewed the film saying that 'How to Murder a Millionaire was made for TV--but not for my TV'.
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Career in pictures Joan Rivers Joan Rivers Joan and her only child Melissa Rivers in 1999. Even though 'The Joan Rivers Show' had ended in 1993, the Nineties saw Rivers make her mark as a stage actress. She was nominated for a Tony Award for best actress for her performance in the Broadway show ''Sally Marr...and Her Escorts'. She also released her book 'Bouncing Back' in 1997 about overcoming bulimia.
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Career in pictures Joan Rivers Joan Rivers Actress Joan Rivers attends the 61st Annual Golden Globe Awards at the Beverly Hilton Hotel in 2004. The previous year she had left her highly popular E! red carpet show to present on the red carpet for the TV Guide Channel, thanks for her caustic style.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers makes a cement impression of her hands during her induction into The Gleasons Walk Of Stars in 2004. She had become a national treasure and was renowned for her acerbic brand of comedy across the world.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers and her daughter Melissa on the red carpet at the 77th Annual Academy Awards in 2005. The pair had a reality TV series called 'Joan & Melissa: Joan Knows Best?' that ran for four seasons from 2011 to 2014. The show documented the relationship between the pair.
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Career in pictures Joan Rivers Joan Rivers Rapper MC Hammer stops at the TV Guide stage to talk with host Joan Rivers at the Grammy Awards in 2005, she was both loved and loathed for acid wit.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers in New York in 2009, the previous year she had taken part in the British 'Big Brother: Celebrity Hijack', where she was given the power to decide the tasks and rules that house mates had to follow for one day.
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Career in pictures Joan Rivers Joan Rivers A still from the documentary 'Joan Rivers - A Piece of Work' in 2010, which followed the comedian, now 76, for a year and was critically acclaimed for its truthfulness.
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Career in pictures Joan Rivers Joan Rivers Joan Rivers visits 'The Tonight Show Starring Jimmy Fallon' back in February this year.
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Her daughter, Melissa, announced the death, in a New York hospital, in a short statement in which she said: "It is with great sadness that I announce the death of my mother, Joan Rivers.
"She passed peacefully at 1.17pm surrounded by family and close friends. My son and I would like to thank the doctors, nurses, and staff of Mount Sinai Hospital for the amazing care they provided for my mother.
"My mother's greatest joy in life was to make people laugh," she continued.
"Although that is difficult to do right now, I know her final wish would be that we return to laughing soon."
Numerous high-profile names have paid tribute to the comedienne , who was known for her acerbic tongue and wit, including Kelly Osbourne, Lena Dunham, Sarah Silverman and Wu-Tang Clan.
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