Unknown . . .
But then, facts, many quite unverifiable, remain unimportant, and everyone is entitled to an "opinion," whatever that may be. Those who tout personal opinions as facts, however, remain guilty of misleading, misinforming and disrespecting all others who hold opposing-though-equally-valid (-vapid) opinions.
Personally, I know of only one deterrent to crime, and that would be a strong, interacting community police force -- you know, those guys in the patrol cars.