Quibble: I.D. hasn't been tested. I don't know how it could be done, but it strikes me that those in the I.D. debate should be able to suggest a way by which genetically manipulated species could be detected.
If they're not sure how to go about it, there's enough manipulation by human scientists that they could look for a possible touchstone between naturally evolved and genetically manipulated there.
I.D. is intriguing philosophy and theologically -- I'm inclined from a philosophic point of view to think it's likely true. But until scientific studies are proposed and carried out to develop methods of identifying intelligently made from naturally evolved organisms there it's not science.
Even if there is no pre-human I.D., such studies may be useful. In the future, we may need to determine whether some pandemic is the result of random mutation or biological warfare.
Actually, there could be evidence of manipulation, but there isn't, which is why the Discovery Institute isn't participating in the trial. They know there is no way to test ID.