Beginning in June 2000, it took Joon-ho Bong a year to write the script for Memories of Murder (2003), yet he has stated that: "For the first six months, I didn't write a line of the script. I just did research."
Joon-ho Bong has stated that the script for Memories of Murder (2003) was directly influenced by Alan Moore's comic book From Hell, and that he was also "a bit disappointed with the Hughes brothers' film of it."
When Kwang-Ho was investigated in the basement of the police station, the two police officers and a suspect watched a TV program while eating their meals. The title of this program is "Soo Sa Ban Jang" which can be loosely interpreted as "Investigation Squad" in English. It was a famous TV detective drama which was aired for almost twenty years. The opening music was also very popular during that time.
Despite the film being based on a series of real murders in the Korean provincial town of Hwaeseong during the 1980s, Joon-ho Bong also drew a lot inspiration from a play called 'Come See Me' which dramatized the incidents, to the extent that he stated in an interview: "If it weren't for KIM Gwang-rim's play [Come See Me], I would have had a lot of problems establishing the structure." While he also gained the idea for the depiction of the era from the graphic novel 'From Hell' by the writer Alan Moore, which was given to Bong by the journalist Tony Rayns as a gift.
One deleted scene shows detective Cho walking in a red light district, and then getting a massage from a girl as he asks her about possible leads regarding the murders. The scene was shot in a real red light district, and they had to ask the local pimp for permission to film.