A woman, aged 81, was assaulted by a bogus charity worker in her Baslow home.
The pensioner told Derbyshire Police that the man claimed to work for Age UK and offered to give her some advice.
Once inside her home in Bubnell Lane he grabbed the OAP, causing a cut to her arm.
Age UK has confirmed that the man did not work for the charity.
PC Linda Hancock said: “We would like to hear from anyone who may have noticed anything suspicious in the area that morning, or who may have any information.
“The woman, and also her neighbours who have heard about the incident, feel understandably alarmed by what happened. I would like to reassure the local community that enquiries are being carried out and officers will be patrolling the local area and speaking to residents."
PC Hancock added: “We would also like to remind residents about advice on dealing with doorstep callers. If you are not expecting anyone, don’t open the door, and then if you do open the door please make sure they use a door chain or bar.
“Always ask for identification then close the door while you check they are genuine by contacting the organisation they claim to be from on a number you have from a directory or letter, and not from a number they give you.
“If someone wants to talk to you about something, don’t invite them into your home but ask them to make an appointment, or to come back, at a time which is more convenient and when someone else could be with you.”
The man involved in the incident, which happened between 10.30am and 11.10am on Thursday, September 14, was in his 70s, wore glasses and a light coloured suit.
He was seen getting into a silver car.
Anyone with information should call PC Hancock at Derbyshire Police on 101.