This concept needs to be rooted out and destroyed, first from the minds of the sheeple, and then from the law. Obviously, someone who was attempting commit armed robbery/murder/rape/etc. IS still a threat to innocent people, after running off into the night. Police often don't catch these lowlifes until after they've harmed or killed their next victim.
What the guy should have said is "they are no longer a immediate threat". (Laughter!)
When a nest of cobras, black widow spiders or youth street gangs take up residence in your community you are under a constant threat. To think otherwise is absurd.
Kipling's tale of "Riki Tikki Tavi" illustrates the point. Nagi (the female cobra) realizes the mere presence of humans in the great house is a threat to her unhatched brood and so plots the death of the humans.The liberal mind set of "when a Cobra attempts to bite you and turns to flee.... you should not chase and kill it since it is no longer a threat" ignores the fact that the bite (crime) was "unprovoked" by the victim and the fleeing Cobra (criminal) will bite again. This behavior goes on until the cobra is dead.