Sorry, I am confused. So you would accept "who would have done it" or not? As a translation of the main sentence here?
@Konrad-Michal: "kto by to zrobił" to faktycznie bardziej "who would do it", ale moja wersja chyba tu też by działała. Ale przyznaję, że reported speech nie jest moją specjalnością.
"Będę wiedzieć" and "będę wiedział" are perfectly interchangeable as far as it is a man saying it.
But I think your answer is valid and I added it. Although probably "Do jutra" (until tomorrow, before tomorrow, tomorrow at the latest) would fit better to translate such a sentence.