Behind your back... you grab a knife that you took from the janitors closet when you were getting the equipment , orange hair was just watching her phone waiting for you to speak , doesn't know a single thing of what your going to do , although you feel like she has a suspicion about you , it's weird but you wouldn't have to worry about that after a few minutes.

You pull the knife closer to orange hair  , you close your eyes because you don't like seeing blood or murder , the second you open your eyes you see orange hair lying on the floor dead in a pool of blood , a knife on the floor all bloody and one witness. You realise you don't want him to find out that you had just killed a person , so the only thing you could do is murder the witness that way no one would find out what you did , you had already set a plan of what your going to do.