Connie Nielsen was the first choice for the role of Valerie Kanon and actually shot part of her scenes, but due to problems of conflict with another set she had to give up finishing the film, she was replaced in the course of work by Famke Janssen.
Liza Marklund, one of the screenwriters of this movie, also co-authored with James Patterson the book "The Postcard Killers" upon which this movie is based.
Finally released as an Amazon Original film in the UK in March 2022.