Does a DPOA have any fiduciary responsibilities to the late principal and her beneficiaries in Florida?

Can a durable power of attorney transfer money into his own personal account from an incompetent person's bank account in the STATE OF FLORIDA; and also use the incompetent's personal credit card for his own PERSONAL use & expenses (food, utility services, gas, restaurants, vet & doctor bills - just to name a few)? Can the durable power of attorney withdraw cash from the incompetent person's debit card on a regular basis? Why doesn't the DPOA have to account for these bank transactions, transfers, withdrawals & credit charges? He says he does NOT have to account for any of the money because he had DPOA & could do whatever he wanted with the principal's money while she was alive. The principal is now deceased and all of this went on during the time she was alive up until the day she died. Is there legal action that can be taken and what are the chances of even winning? There are bank statements and cancelled checks that show all of the said transactions.