It's easy to identify specific crimes and follow them up.
Under this system the crimes in a given district were always committed by strangers rendering identification of the criminal difficult and escape easy.
Even the police, who see the aftermath of terrible, gut-wrenching crimes, aren't forced to watch them actually happening.
But I read about other horrible crimes and abductions where we never receive a tip.
Sardinia has less convictions for serious crimes than any other compartimento of south Italy.