It's has crime in the genre. So, the general gist of what I remember is that there is like 5 murders. There is a detective who enlisted the help a psychology professor to find the serial killer, not knowing that the professor is the serial killer. Meanwhile, the professor is guiding the detective step-by-step on how he went through the murder without showing that he is the murderer. One day, the detective got drunk at the professor's house. When the professor opened the door, the audience sees a ring that belong to one of the victims. I forgot the name though.
Yeah it sounds like Hannibal though I can't remember the ring scene. Picture of the cast above. Spoiler: Hannibal settings In it the detective is hunting a serial killer who is killing people to eat them and he get's the help of Hannibal, who is the serial killer who kills people to eat and serve at his famous dinners to unsuspecting guests.