That is not true. We have solid data from New York during the Giuliani era and more recently Camden, NJ. Whether or not we agree with how they accomplished that is another matter.

For example in New York a massive increase in arrests for nonviolent crime and much more proactively policing in order to check for warrants etc.

The truth is that nothing works in isolation. In New York we also saw a migration of younger professionals back into the city which reduced crime by forcing out poorer residents via gentrification.

The reality is that in any nation with a high prevalence of gun ownership combined with a large portion of the population without enough to provide for themselves and often, due to criminal records, no other choice but to commit crimes to provide for themselves.