Dividend looted by temporary staff blame on Manager and Cashier

My father is working as a bank Manager in a Cooperative Urban Bank. (He is a Asst. Manager asked to serve the position of a Manager due to staff shortage). Recently a temporary staff working in the bank had been getting dividend forms signed saying it's for the members and my father being the signing authority signed it as usual thinking the staff has verified it, but this temporary employee had been looting the dividend money of other members and at last was found out and dismissed. Now the issues had been taken to the level of joint registrar and he had implied that bank staff responsible pay the dividend money looted. The staff held responsible where The Manager and the cashier. My question is that is it the duty of the manager to check who each customer is and then sign the form ? And does the cooperative bank laws define the duty of a Bank manager to an extent where he is responsible to identify each and every customer that he signs the form for ? Can any legal action be taken against the bank for holding my father responsible for the actions of a temporary staff ?