This was a nice short game xD! I liked all the characters (even the killer :3) and the gorgeous introduction.
What could of been improved, however, is it to be not so linear. I mean, letting the player suspect someone and make deductions. If wrong, just give the bad ending.
I also don't get why the killer didn't get the f*** away from there? After all, <the killer> had the letter, right? But I understand it's kinda a fantasy setting ('Undelivered Letters God', LOL!).
Another suggestion is: When interrogating about characters, show the face of the sprite as the icon, matching the character in question. At the beginning, I was kinda lost on who was who.
I had my fun ^^ Good job!