Suntrust Bank Fraudulent Deposit accepted Dunnellon, Florida

The question is against who? 

There is one thing that was not mentioned by the OP, if this was a joint or single return.  The fact that he was able to put it into his Girlfriends account would seem to indicate it is a single return by the ex.  Because if it was a joint the OP should have verified the account before she signed the return.  So everything I am mentioning is based on thinking it is a single return.

Even if the bank is at fault by allowing the deposit, it does not mean that the OP would get the funds.  The best that would happen is that the funds would be returned to the IRS and the IRS would either require him to provide a valid account, or send him a check.

Since this appears to be an agreement between the OP and her ex, she needs to go after her ex in civil court.  Then as to her chances of collecting is what type of agreement it is, such as is it an actual court order for support?

Now, since this is not the OP's return, the OP's account, or even the OP's bank, the OP has nothing to do with this if there was something illegal done, as that is between the IRS, Suntrust and the Ex.

the OP may have a case, if I remember reading it correctly, IRS regulations state that tax refunds can only be placed in your own bank account. If the husband's name did not appear on the girlfriend's account then it was not legal to have it direct deposited to that account. There are many reports on this site of accounts being frozen for this exact reason. So if the bank DID allow it to occur, they could have broken IRS regulations. The OP still can't do anything, its not her money to make a case over.

I mean this is where you lose everyone in your complaint against the bank.  If your husband intended to defraud you, I guarantee you no bank would ever be able to stop him.  The bank has no knowledge of your agreement with scumbag husband - so why blame the bank?  Is it the bank's responsibility to ask why a depositor is putting money into their account at a bank?  Even if they could (privacy forbids it)...do you expect your husband to tell the bank the truth??  Really???

The IRS doesn't know what they're talking about - if you've ever dealt with the IRS as a preparer, you know that to be case.  Your action should be against your husband, and I would use your divorce attorney to not only secure those funds back (if the attorney hasn't done so already), but to seek punitive damages as a result of that attempted defrauding..... that is who your action should be against.  Best of luck to you.

It isn't the bank's fault if your husband deposited funds into the wrong account. It is not clear as to why you think SunTrust allowed your husband to defraud you.