Fraudsters claiming to be clairvoyant and willing to protect people from evil for just £17 are targeting residents in a letter-writing scam.
Police say they have received calls from worried residents across the Thames Valley who have been targeted.
The letters, which are personally addressed to the recipient, claim there is an evil presence which they can be protected from if they send the money.
Thames Valley Police are urging residents to throw the letters away.
Lynne Brooks, who works at Thames Valley Police's Kidlington inquiry centre, said: "There are a number of scams in operation around the country but this one seems more upsetting than most as it uses scare tactics to pressure the recipients into sending a small amount of money.
"Our concern is that as it is a small amount, people may just send it to put their minds at rest."