According to The New York Post's Page Six, which first reported news of Neeson's return to work, the actor was seen sitting alone at the Hazelton Hotel bar alone while in Toronto.
"It was so sad," a source told the paper. "He looked like he was in an Edward Hopper print."
A rep for Neeson told Access the actor has completed shooting of the movie.
As previously reported on AccessHollywood.com, the production team on "Chloe" worked around a missing Neeson following Richardson's death.
Richardson's sister, Joely, also returned to work last week. On Thursday, the actress continued filming the BBC remake of "The Day of the Triffids." Richardson's mother, Vanessa Redgrave, postponed her April 27 NYC performance in "The Year of Magical Thinking" for an undetermined later date.
Richardson, 45, died March 18 after suffering a serious head injury on a Canadian ski slope.
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