Oh nice! This makes sense, for the time constraints you can definitely use what you have as basis to expand on the concept! I think there's potential here.
Also I suggest looking into "a matter of murder" which might have good reference for you. While I don't like motive being used as evidence, in that game they treat it the same as they would a murder weapon, so it's consistent with the game universe and you can have logic apply to some thing that's usually impossible to definitively prove (even a confession can deceive) .