FBI and Banks holds; is this legal ? What can we do?

FBI Hold has been placed on my girlfriends departed fathers bank account, Any suggestions? She verified that account exists with US based attorney but has already had to pay considerable amount of money for outstanding taxes, before bank would release funds, and then when taxes all paid then bank notify her that FBI hold on account, and they are requiring Certificate documents before they will release hold.. And People want payment up front for providing certificates? Any suggestions?