Question about The Investigation sentence (Spoiler)

[ForrestFox]

So I'm a bit confused here. Is there really only one to blame for the poison, or are they all three innocent?
The clues and the motives are strong for each of them.
Would apreciate if someone could give me a straight answer whom to blame of the three choices.

[BaShildy]

Mid-game spoiler All 3 are being set up
Mid-game spoiler You can choose to punish none of them, as there isn't satisfactory evidence that any of them were the killer. If you do Audry falsely confesses in order to make sure you get Ivo's troops and you have to execute Audry.
Late-game spoiler King Ivo planted the evidence, but you can't incriminate him at the trial, that evidence cant be found until later.

[ForrestFox]

Right, thank you. Now I can sleep at night again :)

[MikHaven]

I am OPPOSED to dust sales, in my time as King, so figured, if he was not guilty of one crime he was guilty of another.