Detectives have renewed their appeal for people to be vigilant after a 91-year-old woman was conned out of �6000 in her home.
Police were called to Pleasant Row in Swaffham at about 12.20pm on Thursday after a man visited the bungalow unexpectedly.
The caller said he was there to carry out work on the chimney and needed �150 as an upfront payment, and claimed he had pre-arranged it with the victim's family.
He went inside and confused the victim before stealing �6000 in �20 notes.
Officers from Norfolk Constabulary's Operation Radar team, which specialises in doorstep crime, launched the investigation and are warning householders to be vigilant and not to let in cold callers.
Investigating officer Det Con Colin Aris said: 'About half the cash was made up of old �20 notes which cannot be used in shops. They can however be exchanged in banks and we would urge banks and businesses to be vigilant.'
A 40-year-old man has been arrested in connection with the incident and released on bail while further inquiries are carried out.
Anyone with information should contact the Operation Radar team on 0845 456 4567 or call Crimestoppers anonymously on 0800 555 111.
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