Fraud will happen now?

So i noticed a fraudulent charge on my account in the begining of april... i caught it really fast canceled my card and they put that money back in my account... the charge happened at walmart... They did investigate a little bit and said i need to file a police report... i filed the report so waht is going to happen now... are they going to find out who did it... do the police actually investigate... Like will they pull the tapes at the store... or will the bank... what are the chances of them catching this person... and what if it ends up being someone i know will i have to press charges... How long will it take them to find out I am in idaho by the way dont knwo if that helps