January 21, 2023 

How do we raise the homicide clearance rate? 


PERF members, 

Despite the recent increase in the homicide rate, it remains well below where it was in the 1980s and early 1990s. Unfortunately, the clearance rate for homicides has been on a decades-long decline. In 2020, it dropped to a record low of 50%. 

Chart, line chart

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Source: The Marshall Project 

recent Wall Street Journal article analyzed homicide clearance data from 2018-2021 in 21 cities across the U.S. Comparing data for 2018-2019 to data for 2020-2021, the Journal found that over this period: 

  • The overall homicide clearance rate dropped from 51% to 49%. 

  • The clearance rate for cases involving Black female victims fell from 67% to 59%. 

  • The clearance rate for cases involving white female victims fell from 78% to 73%. 

  • The clearance rate for cases involving white male victims stayed consistent at 58%. 

  • The clearance rate for cases involving Black male victims dropped from 45% to 41%. 

As the National Institute for Justice has written, “the certainty of being caught is a vastly more powerful deterrent than the punishment.” When murderers see there’s only a 50/50 chance they’ll be caught, that may not be enough to deter them from killing someone.  

Al Cardarelli, an outstanding Boston University professor whose class on crime and delinquency motivated me to pursue a career in policing, frequently asks why homicide clearance rates aren’t higher. It’s a question well worth examining. 

For lively discussion on this topic, I recommend you listen to an episode of the Plain English podcast from this past July in which host Derek Thompson interviews crime analyst Jeff Asher. Asher and Thompson consider some possible reasons why official homicide clearance rates have fallen dramatically since the 1960s, when according to FBI statistics nearly 100 percent of all murders were cleared. They include: 1) the data from the 1960s and 1970s is unreliable; 2) the 1966 Miranda v. Arizona Supreme Court decision made it more difficult to solve cases; 3) a growing share of murders are committed with firearms, which are harder cases to solve because police are less likely to have physical evidence or witnesses; 4) staffing declines in police departments have impeded their detective work; 5) prosecutors and juries now have higher evidentiary standards; and 6) poor police-community relations in some localities have made it more difficult to solve cases. 

The suggestion I find least convincing is Miranda. Contrary to conventional thinking at the time, the years since that decision have shown that good homicide detectives can adhere to suspects’ constitutional protections and still get confessions. I agree with Asher that the reported clearance rates from the earlier decades are implausibly high and that the increase in gun-related homicides is the likeliest single explanation for the decline in clearance rates. But it’s worth noting that innovations in firearms investigations, including the use of firearms tracking technologies such as NIBIN (the National Integrated Ballistic Information Network), have proven highly effective.  

It’s also important to understand, as Dr. Charles Wellford of the University of Maryland and James Cronin of the Bureau of Governmental Research have written, that “a law enforcement agency’s policies and practices can have a substantial impact on the clearance of homicide cases and can be increased by improving certain investigation policies and procedures.” Though that report was written some time ago, Wellford has done considerable work on homicide clearances confirming the invaluable importance of managing homicide investigations. 

PERF has identified steps agencies can take to improve their homicide investigations and, potentially, their clearance rates. From 2014-2016, we reviewed homicide investigation policies and practices in a number of sites, and we saw many commonalities. Agencies had dedicated, hard-working detectives operating out of antiquated facilities. Policies and procedures needed to be updated, and many detectives were overloaded. In one department, a single homicide detective was responsible for 30 cases.   

In 2018, with the support of the Bureau of Justice Assistance, we published a report with general findings and recommendations based on our review of those sites. Our recommendations include: 

  • Update Written Policies. Police agencies should update written standard operating policies and procedures (SOPs) that govern homicide investigations. The revised SOPs should include a detailed, step-by-step description of actions to be taken at each stage of the investigation process, as well as mechanisms for ensuring that homicide unit personnel are properly supervised and are held accountable for their performance. 

  • Require Advanced Training for Homicide Detectives. Detectives in the homicide unit should receive training – both upon entering the unit and throughout their tenure in their unit – on advanced investigative techniques specific to conducting death investigations. In addition to the investigative skills taught to all new detectives, homicide unit detectives should receive training on conducting death investigations, constitutional law, advanced forensics and evidence collection, crime analysis, best practices for homicide investigations, and how to investigate specific types of cases handled by homicide detectives, such as officer-involved shootings and child fatalities.  

  • Ensure Adequate Staffing of Homicide Units. A homicide unit ideally should be staffed so that each detective is the lead on an average of four to six new homicide cases per year. This recommendation is based on best practices and on PERF’s finding that an increase in detectives’ average caseload size seems to be correlated with a decrease in their individual clearance rates. 

  • Emphasize the Team Approach. Police agency leaders should prioritize improving cross-agency communication and collaboration and should emphasize the importance of taking a team approach to preventing and solving crimes. This message should be reinforced in written policies and training. Police agencies should consider assembling a homicide investigations team for each case that is led by the primary homicide detective assigned to the case and includes other investigators, a crime analyst, the crime scene technician who worked the scene, the prosecutor assigned to the case, and a designated representative from the patrol unit, the medical examiner’s office, the district detective unit, and any other units relevant to the case. 

I recommend you read or review that report to identify areas where your agency may be able to improve. You might also want to share it with your criminal investigations folks. 

Over the past two years, we’ve seen a sharp increase in homicides and shootings. The agencies responding to the largest number of shootings and homicides have been forced to manage increasing demands on top of their already limited resources. And when departments have trouble staffing patrol, they sometimes reduce staffing in specialized units, including investigations. 

I think the fallout from the killing of George Floyd has also affected the clearance rate. Homicide detectives depend on the community for information, so a lack of trust will affect a department’s ability to develop leads and solve cases. There are countless reasons it’s important to strengthen public trust in the police, particularly because that trust could make the difference in solving one murder and preventing the next one.  

I also encourage you to maintain regular contact with elected officials to share what you think you need to address this problem. Let them know if you need more staffing in your homicide investigation unit, funding for additional training, or more crime analysis capabilities. Many aspects of the criminal justice system have come under scrutiny over the past several years, but I think everyone across the political spectrum wants to know how they can help police do one of the fundamental parts of their job: solving murders.