Help!!! Taxes filed electronically and now wife is saying she did not authorize it!?

My brother filed his taxes electronically to save money and had the money deposited into the family shared account with his wife! His wife is now saying she did not authorize him to sign for her, even though he never signed and said it is fraud! They live together, going through a separation. The money is going into a shared account and it is not a lot! Why would someone be so spiteful!!! Can he get into trouble if you e-file and the spouse now claims she did not authorize it, after she did?