Ann is the more obvious killer who tries to hide it but slips up. Joon is a serial rapist and a murderer who becomes friends with his victims before raping them, killing them in pre-meditated ways and giving his condolences to their family. Peter has grown to be suspicious of Joon but now he fears his life is in danger.
He might survive. Joon seems to like Peter so he might take him to the tower just to show him that he can and that if Peter keeps prying or talks, it won't be him but his family that pays for his mistakes.