When Othello Muhn realised that Maze knew who he was and was on his way, he wrote a letter to Robert Fowler and Hayley Harrison detailing some things they should know, and gave it to his owl Anne Boleyn to give to them when Maze and his minions had stopped looking for her.

The letter:

Hayley and Robert,
There is little time. I will give Anne orders to return then and only then when you are alone, so that no one can read this other than you and those you deem worthy of the secret.
I have been investigating behind Mayhew's back. After what I discovered, I cannot be sure of him, as I cannot be sure of anyone except for you two. I now know things no one else does. Maze is in the castle. He walks the corridors in disguise. I can not know for sure who it is, but I will find out shortly. He has noticed my success and is coming for me as I write this.
Continue where I left off. Find out who it is. He may change his disguise, but there are things that give him away. Maze will try to keep you away from your friends, Hayley. Alone, you are vulnerable. Also, Maze has a dark personality. He can never truly change who he is.
One more thing about my findings. An unfamiliar black owl keeps flying to and from the castle. Attempts to track it have failed. I am almost certain Maze has an accomplice outside of Hogwarts, a truly loyal follower.
I must hurry now. I am giving Anne to you, Robert. She will help you. She knows almost as much as I do and is an extra pair of eyes. In the envelope is a key to the symbolic language she can read and write. Use it.
This letter must be sent now or he will know of it.
Take the torch, I think you are the only one who can,