CHICAGO — Sometimes, all you need is patience to solve murders. Here's how it works: Once a person who homicide detectives suspect of murder dies that's it — case closed.

There's no arrest. No trial or jail time. No justice for a victim's family. The case gets "cleared exceptionally," which is a sub-category of shooting and murder statistics that most police departments don't talk about when they release their annual batting average for solving slayings. So, when you heard, for instance, the shocking news that Chicago police department's murder clearance rate last year was 53 percent — a stark improvement from the 29 percent clearance rate in 2016 — you may have mistakenly believed that meant cops caught more killers last year.

[COMMENTARY] Don't beat yourself up. It's an honest mistake. The murder clearance rate, after all, is fuzzy math, calculated by police department statisticians who don't like to show their work, that misleads the public. I've been writing about the confusing way that shooting and murder clearance rates are calculated for a long time now.

In 2010, Chicago police reported solving 18 percent of the 1,812 non-fatal shootings the year before. More than half of those were cleared exceptionally which means about 91-percent of people who shot-and-wounded someone in Chicago didn't get arrested. In 2012, when 506 people were murdered in Chicago, police reportedly solved 129 killings, a 25-percent clearance rate, the lowest in 21 years. But take away the 12 homicides (9-percent of the "solved cases") that were cleared exceptionally that year, and subtract the 31 murders from previous years that got cleared without an arrest, and you've got a clearer picture of how many people who committed murder in 2012 didn't get arrested.

For decades, City Hall has engaged in a political shell game drawing the public's focus to confusing crime statistics presented in ways meant to sway the public opinion, if only for a news cycle or two, that the current administration has made Chicago a safer place to live.

Opaque statistics used to measure the effectiveness of the Chicago police department's investigative arm charged with solving shootings and murders that plague poor, forgotten parts of town continue to be presented to the public with smoke and mirrors.

In my experience, when a reporter presses Chicago police bureaucrats to explain the city's trouble arresting people involved in shootings and murders they stand by whatever statistical computation results in the most favorable narrative. In October, Chicago chief of detectives, Mellissa Staples, tried a different tact. She blamed a media "misconception" that the police department's homicide clearance rates were as low 15.4 percent.