Chile. A country with over 18 million people, based in one of the most volatile, crime-high continents in the world, has a very impressive set of crime statistics. For every 100,000 inhabitants, Chile sees just 4.30 become victims of a homicide. This may look considerable compared to the UK (1.20), but is very impressive when compared to its neighbours, Peru (7.70), Bolivia (6.30) and Argentina (5.10) and pales in comparison to other nearby countries, namely El Salvador (61.80) and Venezuela (56.33).
Why is this the case? As could be expected, there is no one answer, but a combination of a strong school system and a reasonably stable government can at least partially say why. From what I have found, however, is that it is the deterrent of their police force which can take the most credit. It has been consistently well-funded and with a very strong legal backing, it has the power to tackle knife crime head-on.
Hammersley, R. (2008). Drugs and crime: Theories and practices (Vol. 2). Polity.
List of countries by intentional homicide rate. (2017). From https://en.wikipedia.org/wiki/List_of_countries_by_intentional_homicide_rate