Crime is often caused by an underlying issue and not just a one off case

If we were to solve this root issue then crime rates would naturally drop. An example of it would be a city where theft is common usually has an underlying poverty and wealth distribution issue. If this wealth distribution issue were to be solved by spending resources on welfare towards the poor, then there would be no reason for people to steal. This goes for any other type of crime as well, as humans will usually not act on something unless they have a reason to. So, it is better to spend money to solve the main root issue.