A scene was shot in which Illeana drives back to her house with the old pick-up and a branch from a tree falls and breaks the windshield. It took several takes to get the shot, and apparently destroyed the last remaining windshields for the pick-up available anywhere in North America at the time. The scene was not used.
Despite the fact that the film is set in Montréal, Québec, the police officers are portrayed by French actors who do not have French-Canadian accents, but rather French accents from France.
The source novel's character equivalent to Illeana is James Costa, a British museum curator. Martin Asher's analog is Martin Arkenhout, a native of Holland. The prime settings of the novel are England and Portugal.
This is the second movie that Angelina Jolie has acted in where she plays a character in law enforcement chasing after a serial killer. The first movie was Il collezionista di ossa (1999). Both movies were also adapted from novels.
Screenwriters Nicholas Kazan, Hillary Seitz and David Ayer worked on revisions for Jon Bokenkamp's script.