In Jul 2015, South Korea did announced the removal of time limit on prosecuting 1st degree murder cases, from 25 years.
The series was inspired by real-life criminal incidents in Korea, including the Hwaseong serial murders.
All of the location names are made-up names apart from Seoul and Gyeong-gi. For example Ohsung mountain, jinyang police station, hyeonpoong station
The real life murderer, Lee Chunjae, was identified in 2020. He was already confined in jail for life sentence. He has committed 14 murders at least.