Mr. Smith was found dead in his room. The room has no window and the door was locked. The only 4 people who had a key to the room were questioned by the detective on scene.
Alice the maid: “I came to wake up Mr. Smith; when I saw him dead, I screamed!”
James the butler: “When I heard the scream, I ran into the room, turned on the light and saw Mr. Smith with a knife in his neck.”
Maggie the governess: “I rushed up alongside James; when he turned on the light, the room was all bloody.”
Gustav the cook: “I was preparing dinner and didn’t see anything.”
The detective knew at once who who the murderer was. Who did it?