This chapter's interesting because though he has a better understanding of what taking one's own life means than the old man, their decisions of how to deal when cornered are similarly motivated.
I doubt he's going to be the subject of an investigation. He wasn't being monitored on leaving juvie, because his crime wasn't too heavy. Nobody knows this guy's living in the mountain and even if they do, there's no proof the two ever met, or digitals on the sickle. There might be digitals on the door sill of the room from when he retrieved the bag, but I doubt this would be evidence enough to frame him.
I think the situation will go south for him when he tries to settle down somewhere. It will be very hard to deposit that much money in a bank without having to give an explanation. Or he might draw attention to him inadvertently and be killed for the money.
Or who knows… if he's met Joon Seon, who's to know that he isn't going to meet the serial killer who killed him when he was the rapist on parole? Death seems to be intent on stacking the card deck against him, anyway.