Hamilton police say a man wearing clothing similar to a police uniform asked a homeowner in Mount Hope to use her property for a dog exercise.
This happened Thursday morning.
A neighbour allowed a man who made a similar request to use his property.
Two men were seen walking through the man's yard without a dog.
Police are now asking Mount Hope residents to check their security cameras to help identify the man posing as a K-9 officer.
He is described as white, 35 to 45 years old, with short blonde hair.