to the last comment, You probably made a wrong election of lawyer, but this could also happen in UK. I am sorry about the problems you had or have. I wish you good luck and success.
To the main question, to the observations of my colleage Mr Alfonso I would add that the power of attorney should be limited to a certain period of time. However, think that nobody is going to buy a property for another person without receiving sufficient funds for it.
About taking money from bank accounts, I recommend that the power of attorney entitles only to take nominatives bankers draft, but not cash, so you limit the risk if that person was dishonest.
Juan Bertomeu Vallés
Real Estate& Planning Lawyer