Bad Pants

Thanks to Indiana PD for this item:
A defendant is seeking a new trial after jurors found a confession in pants sent back to the jury room during deliberations.
Ok That's an easy one--new trial. The 'confession' wasn't ever entered into evidence. What's interesting here is the prosecutions position: "Prosecutor David Pascoe said the defense set this up because Banks (the public defender) found the confession when he searched the pants before they were placed in evidence." Hmmm. Interesting ethical question. Let's assume it to be true what happens if you find the actual confession mid trial? What do you do?