Arun George’s review published on Letterboxd:
Having seen a good number of serial killer thrillers from South Korea (including Memories of Murder, The Chaser, I Saw The Devil, The Chase) and almost everything featured in the true crime section of Netflix, I thought I was wholly prepared for this one. The killer (Yoo Young-Chul) is probably one of the most vicious and ruthless beasts you'll ever hear about. While the documentary focuses mainly on the compelling manhunt, it also attempts to humanize the crime divisions of the Seoul police by portraying them as a flawed bunch but with genuinely relatable emotions. It must have been exceptionally tiresome to catch a serial killer with zero motive, utter lack of evidence except for a shoeprint, and the randomized selection of victims. On one occasion, he's targeting a more affluent section of the city, and on another, he's targeting isolated sex workers. But the fact that he escaped after being arrested once is a major stain in the careers of all officers involved.
The whirlwind of emotions that the investigating officers go through is showcased in a believable, non-exploitative manner. Though the makers could have given a tad more focus to the victims, the documentary never falls short of engaging. Each episode is a crisp 45-55 minutes, with the makers not resorting to any odd editing gimmicks or overly stylistic tropes. The team tackles the recreation of some of the gruesome incidents with sufficient flair. They focus solely on the documentary telling a gripping story rather than throwing in oodles of style that dilute its realism. The interviews with the criminal profiler are undoubtedly more interesting as he tries to paint a somewhat vivid picture of what goes through a motiveless serial killer's mind while committing the crimes.