Although based on a true story the names of all law enforcement and victims have been changed in the film. Only the two serial killers in the film retain their real life names.
Ted Bundy and Gary Ridgway are two of the most prolific serial killers in American history. Bundy has 30 official murders on record and Ridgway 49. However it's widely thought by law enforcement that the total for both men is likely to be much higher. Ridgway claims his tally of victims to be as high as 71.
Most of the dialogue between Detective Richards and Gary Ridgway in the police interview scene is based on the real life taped interview between King County Sheriff David Reichert and Ridgway recorded shortly after his arrest.
The concept of the incarcerated Ted Bundy assisting police with the investigation of the Green River Killer inspired author Thomas Harris during research for his novel 'The Silence of the Lambs'.
Exterior footage was filmed in Florida, San Francisco and Washington. All interiors were filmed in Swansea and the Vale of Glamorgan, South Wales.