The Johnsons have just reported a robbery. “All the wife’s jewels are missing. You’ll want to check inside for fingerprints,” Mr. Johnson said to the policeman, pointing to the broken window glasses on the outside of the house. The burglar presumably entered the house by breaking through the window.

The policeman noticed that the inside of the house had a number of very tiny pieces of window glass particles scattered around near the broken window area and replied, “That won’t be necessary. There’s been no burglary.” What made the policeman so sure?