The Death of Edward. B

Inside the classroom, things are surrounded by police tape. You can see the murder weapon on the ground and where the victim died. While looking around, you see a note on ground crumbled up. The note says:

"This is what you get. This is what happens when you mess with the dog
Signed, W"

You keep the note and walk out. You notice that the stairs are blocked and the elevators are turned off.So no one could upstairs or down but have to go out those designated exits. Note the main classrooms in the investagtion are Small Animal Mangement and English but they're on different floors. S.A.M is downstairs while English is upstairs. Take it into consideration of the suspects