This borders on the legal evidence issue of hearsay. Hearsay is "any out of court statement made by the declarant offered to prove the truth of the matter asserted". So if I told you"the color of that book is red", you can not go to court and testify that i said "the color of that book is red", because that would be hearsay and not allowed. With that said, that are a slew of exceptions that will allow certain hearsay statements into evidence as well. So just because the statement made to the cops was not recorded, if a proper hearsay exception exists to allow that statement into evidence, then yes, it can still be used in court.