Detectives in Sheffield are urging residents to be cautious after a series of bogus official incidents across the city.
They are investigating five incidents, but believe there could be more, where a man wearing bright orange high-visibility clothing knocks at the doors of elderly residents claiming to be from a drain cleaning company.
Victims then receive a phone call from somebody claiming to work for the same company who asks for money to be transferred to a bank account.
No work is ever carried out at the homes visited.
Detective Inspector Richard Partridge said: “This sophisticated ruse appears to be targeting elderly and vulnerable members of our community, although it could happen to anyone.”