Three suspected rogue traders were arrested by police after a member of the public believed them to be targeting an elderly woman.
The person reporting the alleged offences believed that the victim had withdrawn large sums of money to pay for work on a property in Duffield.
Officers went to the address and arrested two men, aged 33 and 37, on suspicion of fraud offences.
A third man, aged 33, was arrested at a hotel in Shardlow, also on suspicion of fraud offences.
The three men, who are all from Lancashire, were bailed pending further inquiries. The arrests took place on February 28.
The incident has prompted police to remind people about checking the credentials of cold callers and tradesmen and help protect people against doorstep crime.
The advice includes:
If you are not sure who is at the door, don’t open it.
To check the identity of any caller, confirm who they are by calling the company they work for using number from the telephone directory or a bill.
To ask a neighbour to come around to check them before you open the door.
To tell them to come back at a time when someone will be at home with you.
To keep doors and windows locked and use the door chain every time you answer the door.
To call the police immediately if you feel intimidated, they are suspicious or won’t go away when asked to.
Doorstep traders should legally provide a written form setting out a seven day cancellation period for goods or services over £35 bought as the result of an uninvited visit. A trader commits a criminal offence if they fail to provide the written cancellation notice or if they make false claims about who they are or work for.
Anyone with information should contact Derbyshire police on 101, or call Crimestoppers anonymously on 0800 555 111.