If police say a homicide is 'cleared,' does that mean it's solved? It depends.

Crime statistics can be confusing: The difference between a homicide and a murder. The Uniform Crime Reporting system. The clearance rate.

In the Milwaukee Journal Sentinel’s latest investigation, we analyzed five years of homicides. If a suspect was arrested and charged in a homicide, we tracked the cases through the court system.

The analysis focused on what justice means to many victims’ families — whether a killer was held accountable in court.

It took six months to gather the data and analyze it. The way the U.S. measures crime statistics is not set up to answer that question easily. Here’s are some answers to some common questions about homicide statistics.

How do police departments count homicides?

Police departments count homicides using the FBI’s Uniform Crime Reporting system, which was set up in the 1930s. It is a voluntary system governing more than 18,000 policing agencies across the country.

When police give out their annual homicide totals, what are they really counting?

Police typically are following the FBI Uniform Crime Reporting Program when it comes to defining criminal homicide, also known as murder.

The FBI statistics do not include homicides committed in self-defense, killings by law enforcement or negligent manslaughter cases, such as an accidental shooting. The statistics also do not include fatal car crashes, such as those caused by a drunken driver.

The FBI began collecting some of this information in the 1960s as part of its supplementary homicide reports, but as recent news reporting about police killings has shown, those supplemental reports are still underreported and undercounted.

What does it mean if a death is ruled a homicide?

In forensic terms — something determined by a medical examiner, forensic investigator or coroner — homicide means "death at the hands of another.” It does not always mean a crime was committed in a legal sense.

One common example of this: Fatal shootings by police officers. When a police officer shoots and kills someone, it is a homicide in forensic terms. Often, however, the legal system finds the officer was justified in the shooting because of self-defense. In those cases, the officer does not face criminal homicide charges.

How do we know how many homicide cases have been solved?

Ask practically any police department in the U.S. how many homicides it solves in a year and it will provide what’s known as the “clearance rate.”

A case is added to the clearance list when someone is arrested or when a suspect is known but cannot be arrested. The suspect, for example, may have died or can’t be located, which is known as an “exceptional clearance.” 

A police department determines if any crime is cleared using guidance from FBI crime reporting standards. A case can be considered cleared even if no one is convicted or charged.

Milwaukee police officials say the decision to clear a homicide case is reviewed multiple times by detectives and their supervisors, including the command staff, before being sent to the state officials who then compile the information and forward it to the FBI.

Do law enforcement agencies calculate a clearance rate every year?

Yes. The rate includes all homicide arrests in a given year, no matter when the crime occurred. For example, an arrest made this month counts toward this year's rate, even if the killing occurred years ago.

This means it’s possible for a police department to have an annual clearance rate above 100 percent, even if homicides from that current year remain unsolved.

Why do police calculate their clearances this way?

Because that’s how the FBI tells them to do it. The Uniform Crime Reporting system was created in a time before computers, when police agencies used paper and pencil. Back then, it didn’t make sense to go back and update yearly totals.

What about criminal charges?

Here’s what generally happens in a criminal case: A crime occurs. Police investigate. Officers gather enough evidence, known as probable cause, to make an arrest. Police refer the case and evidence to prosecutors. Prosecutors say they have a higher standard of evidence — “proof beyond a reasonable doubt” — to issue charges. Once a case is charged, a variety of outcomes can follow, ranging from dismissal to conviction to placement in a mental health facility. 

A clearance rate focuses on arrests, while a conviction rate focuses on the charged cases. As you can see, there’s a gap between the two. It’s hard to capture the entire system.

Why does this matter?

If a police agency touts a high clearance rate, but only half of those arrests end in convictions, that often doesn’t mean much to a victim’s family or the wider community.

When someone gets away with murder, it erodes trust between police and the community and may embolden the killer. The cycle feeds itself: a homicide goes unsolved, community trust declines, witnesses hold back and fewer crimes are solved.

More and more research is showing the importance of legitimacy in the criminal justice system — the public must have faith and trust that the system can provide justice. If that breaks down, people are more likely to withdraw from the system and take justice into their own hands.

And that makes everyone less safe.

Contact Ashley Luthern at ashley.luthern@jrn.com. Follow her on Twitter at @aluthern.

READ THE INVESTIGATION:‘My son will not just wear a toe tag’: 233 Milwaukee families seek justice while killers reamin r