How is the financial Director responsible for the wrong doings of his subordinates?

Yes, Financial Director is responsible. Initiating with recruiting of right candidate should be screened for the right job, if anything is going wrong it is duty of his/her higher officer to take a chance of resolving it or clogging of damages causing the organization. 

The task or the job assigned to the subordinates must viewed as a final report or final confirmation, but it is not so easy to keep eye on all the subordinates report, so for that matter it is also a obligation of the subordinate to accomplish the job perfectly without any mistake.