We need to understand more about Chicago’s dreadful clearance rates, which are lower than those of other cities. We don’t expect this is a simple matter of grossly incompetent detective work. If there was an easy fix, no doubt Superintendent Eddie Johnson or Mayor Rahm Emanuel would have embraced it to nab suspects and claim a victory. Instead, CPD’s immediate response to the Aug. 4 weekend violence was to put 600 more officers on the street to prevent a repeat. Yet even that action brought minimal results. Instead of 75 wounded, 12 dead, there were at least 58 wounded, seven dead.