Despite falling crime rates, US "clearance rates" have risen substantially. That is, in recorded cases, fewer arrests or identification of suspects are made. So today a murderer has a forty percent of getting away with it compared to a ten percent chance in the 50's. Why? One reason suggested by Scott Christianson, a former New York state criminal justice official, is;
"Instead of arresting suspects for burglaries and other serious reported crimes, cops today spend much of their energy going after illegal drugs. Their arrest rate for drug possession (especially marijuana) has shot up more than 500 times from what it was in 1965."
It is the job of the state to protect people from each other - not themselves.