Return of money is not a defense in estafa by means of deceit

Dear PAO,

X sold a property to my sister. That property is titled under the name of K. But X convinced my sister that he has lawful authority to transact the property, saying that he is a real estate agent who personally knows K. He even showed my sister a special power of attorney allegedly executed by K. Persuaded by X's representations, my sister paid in full. It is almost a year now, but X still has not given my sister her title. Because my sister was already sensing that X had swindled her, she tried to locate K. She was able to get in touch with K and to my sister's shock, K told her that she did not give X, or any other person, authority to sell her property.