Monster of Chicago

In Chicago 1985, you are an independent private investigator, and a vigilante named as Night Man that Chicago PD hates you and wants to arrest you to put you in prison. You are investigating a cold case of a murder of Allie Loomis and you have a one simple Intel to confirm it was done by a serial killer it was quote left by the monster "Ego amitto larvam, perdo me egreditur a me, sum monstrum"