Perhaps I could respond to that and to your previous question as well. You have to remember that police have a number of tools in their tool box for conducting investigations. To ever say that there was solely one tool over another that would be responsible for solving a crime....
Let's say, for example.... This goes back to your point on preventing crime. In the example that I gave you in relation to the employers of offenders being advised, the difficulty with crime prevention efforts is always how to measure the prevention success. If employees no longer have access to their victims because their employment is terminated, or if for some other reason they don't have access, I think those have to be seen as valuable potential successes of the registry, but unfortunately, I can only say potential.