This is a crossword puzzle based on the Clue board. The answers to the clues at the bottom need to be entered in the squares on the board between the large rooms. The Clue characters' starting spots are shaded with their color; this can help with filling out the grid, since the words on those squares are related to the color (e.g. COMMUNIST for red). Another thing to note is the two words that go down into the green and white starting spots wrap around the corner.
Reading the letters on the bloody squares spells out Dame Mortum's bad habit: her OPEN DOOR POLICY. On the actual Clue board, each room has one or more doors leading out of it. Reading the letters on the squares right outside the doors spells out DA VINCI CODE WRITER, which clues the identity of the murderer, DAN BROWN.