Originally Posted by Space_Coyote

Hire more competent police officers and detectives who can handle the situation. Clearly it isn't a manpower question, since they can apparently lock down ten city blocks with little effort, so it must be a quality problem. Offer police officers and detectives from cities of comparable demographics (but lower crime rates/higher closure rates) good benefits and higher pay than they current receive and replace the idiots you have working for you with decent cops.

If a cop responds to a crime quickly, and investigates properly, the perpetrator can usually be convicted if he is guilty, especially in crimes of passion.