Father's partner transferring money after he died

[Guest]

My father verty sadly passed away on 9th October (a Friday). It was a long illness and not unexpected. As joint executor of his will I called his bank on the following Monday morning to advise them of the death and was assured that no more transactions could now happen and that the only thing that could come out of his account was payment for the will. After a 25 year difficult relationship with his partner (but not wife) I was glad she had no further access to his funds. However I asked for a mini statement recetnly and have just spotted a transction that emptied my father's current account to his savings account on 16th November! Is this fraudulent and can I sue her? Or is it the bank's fault? Just looking for advice really. Any help greatly appreciated.

[des8]

If the balance of your late father's current account has been transferred to his (interest bearing) savings account what makes you think this was a possibly fraudulent action by his partner and not just good thinking by the bank?
What does his partner stand to gain by this movement of funds?