Last week, the Chicago Tribune wrote about the tragic, and unsolved, murders of at least 75 women over the last 17 years on the South and West sides of Chicago.

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Last week, the Chicago Tribune wrote about the tragic, and unsolved, murders of at least 75 women over the last 17 years on the South and West sides of Chicago. According to the Tribune, the women were either strangled or smothered “and their bodies dumped in vacant buildings, alleys, garbage cans, snow banks.”

Arrests have been made in less than one in three of those murders. According to the Tribune, there is no evidence suggesting a serial killer is at work. The absence of a serial killer means 51 murderers have evaded the police and the consequences of their crimes.

Fifty one killers loose on the streets, of any city, is frightening. However, the killers loose on Chicago’s South and West sides only scratches the surface.

Turn the clock back one year — January 2017 — the same newspaper wrote that “More than 80 percent of murders committed in 2016 were not solved.” There were 763 murders in Chicago in 2016. With a clearance rate of 19.9 percent, Chicago’s streets have 612 murderers walking free from 2016 alone.

In the criminal justice system, clearance rate is used to measure the rate at which law enforcement agencies solve crimes. In the FBI’s Uniform Crime Reporting (UCR) Program, law enforcement agencies can clear, or “close,” offenses in one of two ways: By arrest or by exceptional means.

Clearance by exceptional means could include the death of a suspect or the reluctance of the victim or witnesses to cooperate in an investigation.

Declining clearance rates is not just a Chicago problem. If you're murdered in America, there's a one in three chance that the police won't identify your killer.

Clearance rates have declined precipitously over the last 50 years. In 1965, clearance rates for murder hovered above 90 percent. In 2016, the last year of available data, the clearance rate nationwide was 55 percent.

Although homicide has declined dramatically in this country from a high water-mark of 24,530 in 1993 to 16,891 in 2016, solving murders has become more difficult. Even with modern investigative techniques, more homicides than ever remain unsolved.

The scope of the problem is enormous. If you take the total number of murders over the last 10 years and divide that number by the average clearance rate, the result is approximately 54,000 unsolved murders.

More than half of America’s major police departments are struggling to solve homicides at the same level of success they enjoyed just a decade ago, according to a study of federal crime records by the nonprofit Murder Accountability Project (MAP).

The study focused on the nation’s 160 police departments that investigate at least 10 homicides a year and annually report crime data to the FBI’s UCR. Fifty four percent of those departments reported less success in solving murders committed during the 10-year period, 2006-2015, than in the preceding decade.

The problem is about more than police work. The MAP study found most departments with declining murder clearance rates also experienced an increase in homicides. These departments often are located in areas with declining tax bases or facing other kinds of fiscal challenges.

The “no snitching” culture in many minority communities has been fueled by worsening relationships between the police and the public. The reluctance of witnesses to come forward or cooperate with investigators has had an impact on solving murders.

How can the police earn the trust of the public if the most heinous crimes remain unsolved and the perpetrators of those crimes remain free? The mistrust leads to less cooperation, which leads to more unsolved murders which leads to ever-widening mistrust — a lethal cycle that sucks the life out of neighborhoods and whole communities.

— Matthew T. Mangino is of counsel with Luxenberg, Garbett, Kelly & George P.C. His book The Executioner’s Toll, 2010 was released by McFarland Publishing. You can reach him at www.mattmangino.com and follow him on Twitter @MatthewTMangino.