All games in this series have one characteristic: intricacy. It's not how clever the case itself is, but the fact that several people with ghosts in their own minds each carried out their own plans, and unexpected situations occurred. This makes the whole case confusing.
If you want to solve the case independently before the trial begins, you must think outside the conventional wisdom: there is only one murderer. Not everything left on the scene is the result of careful preparation by the murderer, and it may also be an unexpected situation.