If you didn't do, then stick to that. They need to prove you have it. And if you didn't do it, then you can't give it back to them anyway, so caving in and trying to please them won't help you. Just say what's true, and say it consistently. It could still all go horribly wrong against you, because life is not fair, but if you're truly not guilty, act like you're not guilty and you have a better chance of coming out of this okay.