Dohun did kill them, but he also got help from his big brother i believe, he killed the first one by locking him into the warehouse, second one i think he followed him around and the guy was so scared of dying he tripped and fell down the stairs, third one i don’t remember exactly how he died. But his father knows that dohun committed murder, and he knows he did it for Yuwon. His father knows who Yuwon is, he knows everything about him.
I’d have to read it again but from what i remember his father told him to always “give back as much as you get”, when his father learned that Dohun got locked up into a warehouse he asked Dohun whether we was planning on doing what he taught him to. Later in the story, Dohun asks for a house form his dad, the appartement Yuwon and him will share for a short while, but in exchange Dohun would have to do something for his father. At the end of the childhood flashbacks we learn that the thing he has to do in exchange is be his heir to the company and listen to everything he tells him and asks him. In a way Dohun is held in a shackle by his own father.

Spoilers for the stuff duhon idk his name blue hair does
I FUCKING KNEW HE DIDNT KILL THEM NOR DID HE STEAL THE PHONE OR ANYTHING ELSE I WAS A BELIEVER I KNEW FROM DAY ONE HE DIDNT DO THAT SHIT DUDE OMFG CAUSE HOW WOHLD HE KILL THEM IF BOTH HIS ARMS R IN CASTS AND OF COURSE HIS PHONE HAS SCRATCHES IT FELL TWO FUCKING STORIES OMFG DUDE DAY ONE BELIEVER I KNEW HE DIDNT DO THAT SHIT
anyways how r both of their lives so astronomically chopped cooked like dude call this hogu hagyeonsu or stalkers game or hells kitchen the way that their both so chopped in every single regular person ability (I say this lovingly (ish))