Police departments in a number of U.S. cities — Chicago, Detroit, New Orleans — are receiving increased attention for their failure to clear even half of the homicides that occur in their jurisdiction. And note that to “clear” a case doesn’t even necessarily require that someone be convicted of the crime, but only that either an arrest was made or that the case was “cleared by exceptional means,” meaning that the police identified a suspect, had sufficient evidence to arrest, and knew their location, but encountered a circumstance that prevented them from making the arrest.
Of all the crimes classified as Index I crimes by the FBI’s Uniform Crime Reports, murder and nonnegligent manslaughter typically have the highest clearance rate by far.
Source: FBI: UCR 2017 Clearance
What should be realized is just how much lower current homicide clearance rates are compared to the 1960s and 1970s, even though the number of killings in recent years is roughly on par with the early 70s. As can be seen in the following graph, the number of homicides have gone down since its peak in the 90s, but so has the clearance rate.
Source: Murder Accountability Project
An explanation offered for why this is the case is that a growing proportion of these unsolved homicides are gangland killings where witnesses refuse to talk to the police due to anti-snitching norms, low trust in the police, or fear of reprisal. Indeed, the city of Indianapolis has created a witness protection fund in an effort to get more witnesses to cooperate with police.
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