First of all, let me apologize. I apologize for believing that you would be capable of committing such devastating acts against James and Lily...It's been twelve years, and over time it's become easier and easier to accept what the Ministry has been telling us for all these years. I've thought about it so many times, Sirius, and I've never been able to make all of the pieces fit. I've known you since Hogwarts, and turning in Lily and James certainly did not fit your character. But when I read the news that you allegedly attacked and killed Pettigrew, I started to doubt the man I thought I knew. You have to understand, though, that the evidence was compelling. Besides, there was nothing I could do even if I did believe otherwise. They'd already carted you off to Azkban; you were unreachable to me. So, like many of our other friends, I moved on. The grief of James and Lily's passing struck me deeply, and the thought that you could be responsible cut even deeper; yet I still clung to the small hope that maybe the Ministry was wrong.
You may not know, but I have taken the empty position of Defense Against the Dark Arts professor at Hogwarts. During the school year, I have had the great pleasure of teaching Lily and James' son, Harry. He really is a remarkable boy, Sirius, and so much like his parents...Either way, just a few hours ago, Harry approached me with the reason I am writing you this letter. He had somehow gotten his hands on our Marauder's Map! Can you imagine that? Our very tool of adolescent mischief in the posession of one of the founder's son? Using my authority as a professor, I consficated the item. I gave Harry a stern warning about using objects like those, and before he left, he gave me the most astonishing news I've heard to date. Harry said that he thought the map might be broken, as he saw someone who he knows to be dead on it. I asked him who it was, and he said that he saw Peter Pettigrew. I knew right then and there that you were innocent, that the Ministry had the wrong man. Telling Harry that it wasn't possible, I waved off the remark in his presence. Once he had gone, however, I immediately began this letter.
Sirius, I want you to know that I know the truth. I do not know where you are, or what your plans are now that you have escaped Azkaban, but I would like you to know that you know have an old friend back on your side. Your recent "attacks" on the castle lead me to believe that you are somewhere nearby. If you see me on the grounds, you may approach me in your Animagus form. I desperately await your reply, as I've missed you so over these years...It will be nice to chat again, knowing that you are innocent of betraying Lily and James. I am sending my owl out with this letter to look for you in your Animagus form. Hope it reaches you...