CSI Budapest - The Butcher

A cruel serial killer keeps the residents of Budapest in terror. The police captain assigned you, the best team of detectives, to the case to stop the perpetrator. Until now, you have always been one step behind, so the number of victims keeps increasing... Maybe today we will finally be able to put an end to the case?
They came to the abandoned alley at the report of a homeless person:
"I've lived here in the alley for years, but recently I've noticed strange noises from the old butcher's shop. It was as if I woke up to some human scream the other day. One of the neighboring rats chewed on a human finger under the gutter yesterday afternoon. I also looked closely, but he ran into his den with it. My glass is full here, I thought I'd say, still peace is better."
The task of your investigative team is to find out if it was just the alcohol talking about the old man, or if you are on a hot trail and here is a great opportunity to catch the bloodiest killer of the century!