Schindler's List star Neeson rushed to her bedside at the Hopital du Sacre-Coeur de Montreal as doctors battled to save her. He flew her to Lenox Hill Hospital in New York on Tuesday, where he was joined by the actress' mother Vanessa Redgrave and close friends and family.
She was removed from life support on Wednesday morning and died hours later.
Confirming the sad news, the actress' publicist Alan Nierob tells WENN, "Liam Neeson, his sons, and the entire family are shocked and devastated by the tragic death of their beloved Natasha. They are profoundly grateful for the support, love and prayers of everyone, and ask for privacy during this very difficult time."
The daughter of late director/producer Tony Richardson and actress Redgrave, Richardson began her career in regional theatre before moving into television and film work.
She also portrayed heiress and socialite-turned bank robber Patty Hearst in a biopic and played Lindsay Lohan's mum in the 1998 remake of The Parent Trap.
Richardson won a string of honors during her career, including a 1999 Tony Award for Best Actress in a Musical for her turn in Cabaret on Broadway.
She also scooped the Plays and Players Best Actress in 1990, and was twice honoured with Britain's Evening Standard Film Award - in 1990 and 2006.
Richardson wed filmmaker Robert Fox in 1990 but they split two years later. She married Neeson in 1994.
She is survived by her mother, her sister Joely Richardson, half-brother Carlo Nero, and her two sons with Neeson, Micheal Richard Antonio, 13, and 12-year-old Daniel Jack.
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