OP typed "fl" so I guess this is Florida. You may check the public records for the county where your father lives (and has lived). There may be a POA on file with the Clerk's office. There is also the possibility that he left a POA with his bank or some other financial institution. Also, check with his physicians to see if a Medical Surrogate has been filed with them. Many times these documents are drafted in conjunction with a POA and it could give you insight as to who may have drafted a POA (if an attorney did it). If he is in a nursing home, they may have a copy of one, if he executed one.
You said that he was deemed incompetent. Who deemed him incompetent? The legal determination of competency can only be made by the court. Therefore, there should have been a guardian appointed by that court. The guardian will have the authority to act on behalf of your father with court oversight.
If the legal determination has not been made you can petition the court in the county where your father lives to make a determination. You can also ask that you be named the guardian.
You will likely need to obtain the assistance of an attorney to guide you through the process efficiently. The process in Florida can be a little tricky, but is usually not overly burdensome.
Hope this helps, and good luck.
