If there is no will and subsequently no appointed executor of the will, this matter is decided in probate court. The probate judge will utilize the intestate succession law to dictate who will be appointed the executor of the estate. A letter of administration will be issued to the appointed executor authorizing them to carry out their responsibilities.
The executor of the estate is not the same as Power of Attorney (POA). At the time of death, Power of Attorney is no longer valid. The only exception to this is with a non-durable Power of Attorney. This form of POA ends only when the individual is deemed incompetent.