Detectivefilesinspired Stories

This story is about the unsolved murder cases of Mujin City. Mujin City is known to be the "City of Murderers". The term "murderers" is referred to one person who is the real killer of all those victims. It is murderers because the killer has so many faces who remains to be unknown. The cases were stucked for five years until there is a newly assigned detective who started to investigate about these cases. The detective is also mysterious. The questions are, how will the new detective solve this complicated cases? Who is the real killer? What is the reason why did he/she killed those victims?