Ryan, I really appreciate the time you took to give me your feedback thank you.
The final call works like this: the wrong suspect gets the bad ending. With the right suspect, you need the right motive and two cards that actually prove it to get the best ending. Miss either one and you get the partial ending. Some clues are true and feel strong, but they only support the story and don't prove it. I suspect one of those slipped into your two picks. You're right that the game should tell you which part fell short. In the full version I have been working on, the ending screen marks the culprit, the motive and each piece of evidence separately, and it says why a weak card didn't hold up.
Again, huge thanks for the feedback and I am glad you found the game fun.