Killer in the school

You step into the heads office. Suprisingly everything is as it should be until you notice the trail of blood under the headmasters desk. Going around the desk you see the heads body. Thinking he is dead you begin to leave when his body twitches. You turn him over and his eyes open. "Its not over yet" he whispers "you can still save the school but its too late for me. Before I go I can offer you this advice:
The library may be near,
but continue to fear,
the hooded killers deadly link,
because he is closer than
you think.
With that he is dead. You, Andrew and Cameron have decided you have seen enough. All 3 of you leave the heads office and continue to the library.