Mafia 21.

Okay, I should check the evidence on the serial killer, and now I'm very doubtful about Happy. On the second night, she was blocked, and all the town's non-magic roles were present, except for the Sorceress. Today, she was blocked again, but this time, the Sorceress was present. Therefore, Happy is most likely not a town member...

Added after 47 seconds

He died from multiple stab wounds, resisting death until his last breath.

Features: "last breath" - kills the attacker (he dies himself).

KO seems to be hinting at something.