BOGUS officials are one group of criminals being targeted by Operation Lancelot officers.
Of the ten burglaries committed in Sedgefield borough since the start of November, two were carried out by people posing as water board officials.
The burglaries were committed in Aycliffe Village and Spennymoor by the same people using the same method.
Similar incidents have been reported in Durham City and Chester-le-Street in recent days.
Police are urging the public to keep an eye on elderly and vulnerable people.
Detective Chief Inspector Colin Pearson said: "Everybody who lives in a normal street will know someone elderly or vulnerable. I am asking people to talk to them and let them know that if anybody comes and knocks on their door, they don't have to let them in."
He also urged people not to be afraid to contact police if they have any suspicions.
A number of calls were recently received about door-to-door callers in Sedgefield village, who turned out to be working for a charity.
DCI Pearson said: "As it turned out, they were from a legitimate charity but the police went out straight away and gave them a little bit of advice. We don't mind that at all because we don't want people thinking the police are too busy to speak to them."
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