An 83-year-old man from Oxfordshire has been conned out of more than £15,000 in a postal scam.
The man, from the Kennington area, received a letter in July claiming he had won the Spanish Lottery.
The letter said in order to claim the prize, he needed to pay expenses and taxes to the Spanish government and EU.
His bank grew suspicious and urged him to contact police after growing concerned that 17,646 euros had left his account since July.
Pc Ben Wilson said: "This sort of crime exploits the most vulnerable people in society, preying on their good nature and expectations.
"Fraudsters hide behind the identities of companies, government bodies and legal organisations to try to legitimise their scams.
"In this case the victim has been left extremely upset by the incident, but wants us to publicise what has happened so that no-one else falls into this trap."
He urged anyone who received post they feel is "not legitimate" to contact them.