An elderly couple were targeted by bogus water officials in Withington.
At about 2.25pm on Friday 4 January 2013, two men knocked on the door of the house on Alan Road.
They told the elderly man and woman, both 86, that they were from the water board and needed to put blue dye in the water.
The victims then led the men to the kitchen, but the 86-year-old man noticed that one of the men had disappeared.
He then went upstairs to investigate and found one of the men going through his drawers and personal belongings.
The victim challenged the man and both men then left the house empty-handed.
They are both described as being white men in their late 20s to early 30s, with a heavy muscular build. They were wearing overalls and spoke with Lancashire accents.
Detective Constable Fiona Manning said: "While the victims feel cheated by the actions of these men, this could have been a more distressing incident had they not realised what was happening.
"I am appealing to anyone who may have been in this area at the time and may have seen men matching this description.
"We would also like to remind residents that the water board is no longer in existence and that anyone who visits must be asked to provide ID."
Anyone with any information is asked to call police on 0161 856 4423 or call the independent charity Crimestoppers anonymously on 0800 555 111.
Tips on how to avoid becoming a victim of bogus callers:
- Remember to keep all external doors locked at all times, whether you are at home or not
- Stop and think before you open the door. If possible, look out of the window or use a door viewer (spy-hole) to check whether you know the caller
- If you have a door bar or chain put it on before opening the door and don't open the door until you are happy with the caller's identity
- If you have not got a door bar or chain, ask the caller to push their identity card through the letterbox, then check the photograph corresponds to the caller
- If you still have any doubts, ask them to call back when either a family member, friend or neighbour can be present. Genuine callers would never wish to cause distress, and would be happy to call again