I totally rolled 3 elements into that one is a red eye, caused the main theme is whodunit and eye always mean thorough thinking and sharp insight. In another hand, I set its colour being red and put it at central of the whole cover which is really striking and easy to find.

As we know, whodunit always is confusing and thought-provoking that lead me to put a big question mark inside but I got an inspiration from online that rolled question mark and a shape of the head into one which makes reader feeling that shape of the head is themselves and thinking more creatively.

For the colour, the main colour is green caused the story happened in a forest and
illustration colour is red which looks more bright if put on the green background.