For two weeks, Kim’s gang scoured the underworld of Seoul looking for the man with the crowbar. They eventually found Yoo in a hospital, where he was recovering from the injuries Kim had inflicted. Kim reportedly walked into the hospital room, grabbed Yoo by the throat, and whispered something akin to: "I don't know who you are, but if I see you again, I will kill you." Here is where the film diverges from reality. In the movie, the detective (Jung Tae-seok) has no leads. He is frustrated, departmentalized, and desperate. He needs the gangster’s help.
The Gangster, The Cop, The Devil succeeds because it uses the skeleton of a true crime story to build a muscular action epic. The film asks us to imagine a world where a gangster is the lesser of two evils, and a cop must become a devil to catch a devil. While that specific scenario never happened in a Korean police station, the fact that it almost did—the fact that a real mob boss beat a real serial killer to a pulp—is exactly why the movie feels so terrifyingly plausible. is the gangster the cop the devil based on true story
Furthermore, the "mob boss" Kim Tae-chon never entered into a formal alliance with the police. Kim was arrested shortly thereafter for his own crimes (including violence, blackmail, and running gambling dens). He only told the story about beating up the serial killer to the press after he was in prison, likely to boost his reputation. For two weeks, Kim’s gang scoured the underworld
| Element | In The Gangster, The Cop, The Devil | In Real Life (Yoo Young-chul / Kim Tae-chon) | | :--- | :--- | :--- | | | Serial killer stabs mob boss; boss survives. | Serial killer attacks mob boss with crowbar; boss wins the fight. | | The Alliance | Gangster and Cop form an official, secret pact to catch the killer. | No alliance. The police were already investigating. The gangster hunted the killer alone. | | The Motivation | Cop wants justice; Gangster wants revenge for his wounded pride. | Gangster acted purely out of pride and territory protection. | | The Ending | The cop arrests the gangster after the killer is caught. | The gangster was already a wanted criminal. Both the killer and the gangster went to prison separately. | | The Killer | A young, handsome, smiling psychopath who kills randomly. | A middle-aged, awkward construction worker with specific hatred for rich people and sex workers. | | The Daughter | The killer targets the gangster’s daughter. | No such relationship existed. Yoo targeted strangers. | Why Did the Filmmakers Change the Story? Director Lee Won-tae had a specific goal. He wasn't making a documentary about Yoo Young-chul; he was making a genre film about the blurry line between law and crime. The true story provided a fantastic hook —a gangster hunting a killer—but it lacked narrative symmetry. In the movie, the detective (Jung Tae-seok) has no leads
In reality, Kim Tae-chon just beat the guy and let him go. That makes for a funny anecdote, but not a two-hour thriller.
In the real 2004 case, the police were already several steps ahead. When Kim Tae-chon was beating up Yoo Young-chul in the street, police were already investigating a series of murders that Yoo had committed. In fact, Yoo was already on their radar via a separate investigation into stolen golf clubs.
Yoo Young-chul attempted to murder Kim Tae-chon using a crowbar near a karaoke bar. Unfortunately for Yoo, he had picked the wrong target. Kim was not a random civilian; he was a trained fighter and a brutal criminal enforcer. Despite being bludgeoned, Kim fought back. He overpowered the serial killer, disarmed him, and proceeded to beat Yoo unconscious.