The 'Bel Ami' actress, 34, looked slim in a black-and-white frock while promoting her eight-part Lifetime series 'The Lizzie Borden Chronicles', reported Us magazine.
Ricci first played Borden, a Massachusetts woman who killed her stepmother and father in the 1800s, in the TV movie 'Lizzie Borden Took An Ax' in January 2014.
"I think she's a really fun character to play. I mean, she's out of her mind and a bad person and she likes to commit murder. So, I just go to a place where things are fun and dark," she said about her role in the upcoming, fictionalised series.
Ricci and her husband James Heerdegen welcomed a baby boy past August.