The YouTubers Are: The-Diamond_Minecart, Stampy-Cat, Stacyplays, DCShadowLady, Sparkles, TourkDog and CassieRose
We do not know who the murderer is but this person uses lots and loots of ender pearls and currently has lots of traps going on to kill everyone of then to get there stuff until she/he gets the enchanted flint and steal!