Does this mean cops in Albuquerque are nearly five times better at solving murders than the ones in Buffalo?
Not exactly. Impressive clearance rates are often trumpeted in press releases and news conferences, but how they’re reported is open to interpretation. Sometimes the resolution of a case is beyond a police department’s control.
Data recorded in the FBI’s Uniform Crime Reporting Program show just how widely clearance rates vary across larger police departments. Of the 100 cities reporting the most murders in 2013, 11 cleared less than a quarter of their cases. Meanwhile, eight departments registered clearance rates of 90 percent or more. The national murder clearance rate was 64 percent for 2013.
One statistical complication is that the FBI counts clearances for crimes committed in previous years as part of current-year statistics, while prior annual rates aren’t revised. This is why Fayetteville, N.C., and several smaller departments actually recorded murder clearance rates higher than 100 percent for 2013.
There are many reasons why clearance data vary so much from one city to another. The most common way for a case to be cleared is if a suspect is arrested or charged, but the FBI also allows for clearances by “exceptional means” when charges are not filed. Sometimes this is because a suspect has died or witnesses decline to testify, but different departments might clear cases this way under a litany of circumstances. It’s another reason why it’s difficult to draw conclusions from the numbers. “I don’t think it’s a measure that law enforcement wants people to really study,” says John Boulahanis, a Southeastern Louisiana University professor.
Boulahanis researched Chicago’s murder clearance data from the 1980s and 1990s and found that “exceptional clearances” accounted for as much as 20 percent of the cleared caseload in any given year. What stood out to him was that the majority of these cases were labeled “barred to prosecution,” meaning that police had identified their suspect, but prosecutors declined to authorize an arrest. Examining the individual cases revealed that cleared murders were disproportionately more likely to be barred to prosecution if they involved African-American victims or occurred in police districts on the crime-plagued South Side of the city. Closing cases this way not only boosts an agency’s clearance rate, but also means that prosecutors don’t handle as many of the tougher cases that can take a toll on their conviction rates.
Types of murders further explain the variation in cities’ clearance rates. In Chicago, as in other cities, gang- and drug-related killings are particularly hard to solve, as witnesses often don’t cooperate. Domestic-related cases, by comparison, generally aren’t as difficult to clear.
In Boston, police reserve exceptional clearances for only the rarest of circumstances, about one case every few years, says Robert Merner, who heads the department’s Bureau of Investigative Services. “It’s not just about the rate itself,” he says. “It’s that we’ve provided a sense of justice to victims’ families. When we put handcuffs on people for murder here, they’re found guilty.” Merner reports to both the city police commissioner and Suffolk County district attorney, an arrangement that he says promotes a shared responsibility for both clearances and separate conviction rates that measure how often prosecutors secure guilty verdicts and pleas. Suffolk County’s murder conviction rate has hovered between 85 and 90 percent over the past decade; the national average for large urban counties is 70 percent, according to the Bureau of Justice Statistics.
The manner in which agencies clear cases and the types of crimes occurring undoubtedly affect clearance rates. But there are operational steps agencies can take to improve.
For a 2013 report, the U.S. Department of Justice studied a small group of police departments with high murder clearance rates to learn how they had achieved them. All departments, the study found, benefited from strong levels of trust between police and citizens in their communities. In high-performing agencies, patrol officers who had already developed relationships with residents canvassed neighborhoods for information. In other agencies without the same relationships, police might perceive canvassing as a waste of time unlikely to yield much new information.
With advances in technology, one might assume that murder clearance rates would be improving. To the contrary, national rates have changed little over the past 20 years after falling steadily in the decades before that. In the 1950s and early 1960s, more than 90 percent of homicide cases were cleared nationally. Steven Brandl, a criminal justice professor at the University of Wisconsin–Milwaukee, attributes part of the decline to an increase in drug-related and random killings that are difficult to solve. In some cases, he says, DNA evidence may be excluding suspects who would have faced a conviction in the 1950s, contributing to the overall clearance rate decline.
Police feel the most pressure to solve high-profile cases occupying the media spotlight. But an unusually low overall clearance rate may also attract attention and become an issue for a police department. Pittsburgh recorded its highest homicide tally since 2008 last year, prompting police Chief Cameron McLay to declare a “public health emergency.” The city’s clearance rate for the year was 41 percent, concerning some local groups who felt that murders in their neighborhoods weren’t receiving enough attention from police.
It’s an illustration that regardless of how clearances are defined, solving murders can go a long way in establishing a community’s trust.
