You get what you measure.
What would you say is a good measure of an effective police officer?
Would you say percentage of closed cases? Because that's what leads to this.
Would you say, the number of crimes reported per capita? Because that's what leads to this.
It's unlikely you'll find these people or catch them on average. You may get them for something else and be able to close several cases at once, but the truth is you'll just never see them again. So if you take the report and open a case, your numbers look bad. Crime per capita is up, percentage of closed cases goes down.