"Because I left it there for you. The keys, the diary I left them all for you, I planned every single action you took to lead to this very moment right now...
It is true I destroyed all evidence of her presence in this school, I was compelled to do so although how you got to find out is another thing I don't know but anyway, I have eyes and ears everywhere so immediately I knew you had found out I decided to lay the only surviving possession of Cynthia as a clue and you were smart enough to retrieve it" she smiled
I was dumbfounded after hearing everything she just said
She chuckled " You don't believe? Then why would anyone leave such important bunch of keys laying under the door mat? And I'm not that stupid to give a student a spare key to my office, I would wait till the call was over then lock the door."