South Yorkshire Police have released a description of a bogus official targeting homes in Sheffield.
The woman is reported to have been preying on vulnerable people in Ecclesfield and Parson Cross and asking for money, some of which has been handed over.
Officers say the woman has long dark hair, wears a baseball cap and has flared trousers.
A police spokesperson said: "Please be aware and do not let anybody into your house without checking their identification.
"If you know of a potential vulnerable neighbour then please keep an eye out for them."