The police might still have a case if you let them in and they find something illegal. Giving them consent without a search warrant can make a difference. If they entered forcefully without a search warrant it will also make a difference to the case. Consult a lawyer and be advised on the best course of action to take.
here in Houston they don't need a search warrant, they are allow to kick your door in with the blessings of our mayor..and if its the wrong door its considered let that be a warning to others..We are the LAW.