The thief who wanted to be found

Amina Gray is a second year student at the elite school Hivey University, in the academic city of Oxford. As she is trying to figure out a way to show her parents she has the abilities required to do her dream job - becoming a detective - she reads in the newspaper that a book coffer has been stolen from the famous Bodleian Library. This simple-looking case looks like the perfect opportunity to show her parents what she is capable of.
That is, until she finds a note addressed to her on the scene of the theft with a threat.
Who is the thief ? How do they know her ? What do they want ?