El sustituto

Screenwriter J. Michael Straczynski first learned of the story of Christine Collins from an unnamed source at Los Angeles City Hall. The source had stumbled across case files regarding the Wineville Chicken Coop Murders among other discarded documents scheduled for destruction. Straczynski took the files and became obsessed with the case, doing extensive research over the course of a year. He tried to make it into a television project, but never found a solid way to do that. Virtually every event depicted in this movie appears as cited in legal documents, with dialogue often taken verbatim from court transcripts. Straczynski wrote his first draft of the screenplay in only 11 days.

Detective Ybarra uses the term "serial killer," coined by FBI Special Agent Robert K. Ressler in the 1970s.

The black-and-white Universal logo used in the 1940s opens the film.

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