There are evidence-backed ways of reducing criminality.
One counterintuitive way of reducing crime is to increase the likelihood of being caught, to have small-but-increasing consequences for committing crimes, and to increase the swiftness of sentencing.
For example, if you are caught drinking and driving, you immediately spend 1-2 days in jail.
Long sentences are not very productive at reducing crime or at least are a very inefficient way to do so.