Actress Natasha Richardson died March 18 in a Manhattan hospital after she was declared brain dead and taken off of life support. She died shortly after at the age of 45.
Neeson and Richardson were married for 14 years and have two sons.
The New York Post said Neeson returned to work on the film "Chloe," in which he co-stars with Julianne Moore, late last week, just days after burying Richardson near their home in upstate New York.
Neeson reportedly was seen sitting alone at the bar of the Hazelton Hotel in Toronto where he had been wrapping his last scenes for the movie following a brief break.
"It was so sad," a source told the Post. "He looked like he was in an Edward Hopper print."