When wrapping up a case the player can accuse different suspects, with different results. There is, however, only one correct choice which can be achieved finding a specific set of clues (although the order in which the investigation is performed is up to the player).
It's also possible to correctly solve a crime (i.e. accuse the right culprit) but not get the best ending of that particular case (for example, failing to find out where the criminal is hiding).