Deuteronomy 21:2
Then thy elders and thy judges shall come forth, and they shall measure unto the cities which are round about him that is slain: Then thy elders and thy judges shall come forth, and they shall measure unto the cities which are round about him that is slain:
The elders and judges were required to come out to the place where a person was found slain by an unknown killer and measure from the body to the cities round about. That measuring identified which city was nearest to the slain man, and that nearest city was then held responsible to carry out the prescribed public ceremony. By this requirement the local authorities were made responsible for responding to an unsolved killing, not treating it with carelessness or negligence but showing abhorrence of the crime and seeking justice by every possible means.