For the citizenship would be good if they didnt have the naturalization certificate right?

Wildspirit we dont know...Its what we are trying to find out but we dont know how...

Hi...My girlfriend is applying for dual citizenship here in Italy...The Comune of my city asked for a certificate of non naturalization, a certificate that says that the grandfather of my gf didnt get the american citizenship losing the italian...What is this document?? How can we get it??
Thanks...