Police have issued a fresh warning for residents to be vigilant against bogus callers and opportunist burglars.
The warning comes after a man posing as a "water board" official tricked his way into the home of a 91-year-old woman in Eggborough near Selby.
During the afternoon of Thursday 7 July, a man claiming to be a water official called the woman's home and asked to enter the property.
The elderly victim allowed him in to her home and thought nothing more of the incident, believing him to be genuine.
It was only later in the day, when a member of the public returned a discarded personal document to her house, that the victim realised she had been burgled.
Personal items, an amount of cash and a set of car keys were taken in the burglary.
Police are advising all residents to be on their guard against anyone who calls at their home who they do not know or are not expecting.
In another incident which took place in the village of Wheldrake near York, burglars targeted a woman in her eighties and stole cash from her house after entering through an insecure door. The woman saw one of the men coming out of her bedroom before they left with a box containing cash.
Detective Inspector Ian Dyer of York CID, said: "Targeting the elderly and most vulnerable members of society is deplorable. The victims in these cases have been left very shaken and distressed.
"It is often difficult to convince elderly people not to let strangers into their homes because they believe it is not polite to keep someone on the doorstep. I would therefore encourage anyone with elderly parents or relatives to speak with them to reinforce the message not to allow cold-callers inside."
He added: "Never let anyone in who you don't know, use a door chain or sign up to our nominated neighbour scheme. Locking doors, even while you are in the house, is a must and do not leave tempting valuables on view.
"Many burglaries are committed by opportunist thieves who literally see an opportunity to steal something and take it. Usually because it has been left on view, unlocked or unattended."
Police are appealing for anyone who saw any suspicious activity or vehicles in the Wheldrake or Eggborough area yesterday, or can help identify the men to get in touch.
Officers would also like to hear from anyone who thinks they may have been targeted by the men, to contact police.
Anyone with information is asked to contact York CID on 0845 60 60 247.
Police are carrying out reassurance patrols in the area and are available to discuss crime prevention advice.
4.28pm - 8 July 2011