He ignored the plea for help by je-oh. That time je-oh was still a child when his father tried to murder all of them by burning coal briquettes in house. Je-oh's mother died, je-oh and his father survived. The investigating officer was that police guy. Je-oh pleaded help from him to move from his father, but the police guy ignored him. A few years later, the police guy met je-oh in the red light district. Je-oh confronted him and the police guy had been feeling guilty ever since.
He ignored the plea for help by je-oh. That time je-oh was still a child when his father tried to murder all of them by burning coal briquettes in house. Je-oh's mother died, je-oh and his father survived. The investigating officer was that police guy. Je-oh pleaded help from him to move from his father, but the police guy ignored him. A few years later, the police guy met je-oh in the red light district. Je-oh confronted him and the police guy had been feeling guilty ever since. Fast forward to present time. He met je-oh to confess and apologize about this. Je-oh got pissed and asked him to own his actions like an adult. Because if he had help je-oh at that time, je-oh would not be a male prostitute at the red light district. That's why he helped je-oh. To reduce the weight of his guilt.

What does that guy, police officer, the one who had the kid shoot out the cameras, have to do with je-oh?? bc they clearly have history but I forgot and I don't wanna re-read.
My theory is that he's one of the corrupt officers who turned a blind eye to the trafficking and worked with the guy from the red-light district.