June 28, 2025

Developing a training curriculum for investigative supervisors 50 years after the RAND study

PERF members,

Nearly 50 years ago, RAND published a landmark study of criminal investigation practices. The research included a national survey and “interviews and observations . . . in more than 25 departments selected to represent different investigative styles.” RAND got permission from police chiefs to have researchers ride along with detectives.

The study advanced our knowledge of how cases were solved, identifying “solvability factors” that could help agencies determine which cases detectives were most likely to close. But the researchers found that detectives’ efforts had little impact on whether or not a case would be solved. “Only about three percent of all index arrests appeared to result from special investigative efforts where organization, training, or skill could make any conceivable difference,” researcher Dr. Peter W. Greenwood later wrote.

(As a brief aside, when I worked in the Boston Police Department [BPD], I heard that when the RAND researchers briefed BPD officials about their findings, they mentioned detectives attended to personal business like picking up dry cleaning and visiting significant others while on the job. That wasn’t something BPD leaders were expecting to hear, and the researchers and BPD officials were left wondering what the detectives did when they weren’t observed!)

Significantly, in the decades since, new research has contradicted that finding. Experts on this topic, such as Professor Cynthia Lum of George Mason University and Professor Emeritus Charles Wellford of the University of Maryland, have discussed how the research has changed.

“More recent studies on police investigations have indicated that there is more to predicting crime clearances than case characteristics and solvability factors,” Professor Lum, Professor Wellford, and others wrote in a 2024 Police Quarterly article. “Scott et al. (2019), Vovak (2016), and Worrall (2016) have all discovered that agencies across the U.S. vary in their long-term patterns of crime clearance. Some agencies consistently perform much better (or worse) than the national average in terms of clearance rates for specific types of crime. In addition, evaluations of specific agencies suggest criminal investigations can be improved through better management, training, policies, use of technology, and investigative techniques.”

I asked Professor Wellford to elaborate on this point. “[The RAND] finding stood until researchers began to study investigations using case files and interviews with investigators, allowing them to understand investigations at the case level,” he wrote to me. “These studies also considered the role of police and specifically detectives for specific types of crime. Although the focus of this research has been on homicides, in recent years research has also focused on robberies, assaults, sex crimes, and burglaries. This research has clearly demonstrated that how police organize, investigate, and manage homicide investigations is more significant than case, offender, or victim characteristics in explaining homicide clearances.”

A decade ago, PERF reviewed homicide investigations in a number of large jurisdictions at the request of the Bureau of Justice Assistance. The findings were published in a 2018 report and aligned with Professor Wellford’s observations. Contrary to what the RAND studies found, we saw that management makes a difference and that today’s investigative supervisors are highly engaged with their detectives! But despite the field’s improved knowledge of criminal investigations, the homicide clearance rate has steadily declined over the decades and varies widely from agency to agency. I wrote about this drop and some possible explanations for it in this column in 2023, and I remember regularly speaking with one of my mentors, Al Cardarelli at Boston University, about this subject.

PERF has observed there is no uniformity or best practices for supervisors managing investigations. In an effort to improve criminal investigations, this week we hosted a meeting to discuss a training curriculum for investigative supervisors. This project is funded by Arnold Ventures, which has prioritized identifying ways police departments could more effectively solve crime. Based on this meeting and additional background research, PERF will develop a curriculum to better equip investigative supervisors for their jobs. We will then look to test that curriculum in the field.

Attendees at this week’s meeting included chiefs, deputy chiefs, captains, lieutenants, and sergeants from across the United States who are involved in supervising investigations. We also heard from police officials in Canada, the United Kingdom, Germany, France, Australia, and Japan, as well as researchers who study policing and a prosecutor. Attendees discussed key aspects of supervising investigators, including the following:

• Managing investigations
• Applying solvability factors
• Conducting case reviews
• Cultivating partnerships
• Leveraging technology
• Selecting detectives
• Conducting performance evaluations
• Creating a culture of wellness

You’ll see those topics addressed more thoroughly in the final training curriculum, but I’d like to briefly share a few of my highlights from the discussion.

• Frauke Schlembach, Senior Police Liaison Officer with the German Embassy, discussed the challenges of managing investigators who are seen as “rockstars.” She also said new supervisors may not be prepared for the loneliness that can come with becoming a manager.

Frauke Schlembach, Senior Police Liaison Officer with the German Embassy.

• Legendary LAPD homicide detective John Skaggs, who was featured in Jill Leovy’s book Ghettoside, spoke about the importance of creating a culture of excellence.

Retired LAPD Detective John Skaggs.

• I raised the question of how much investigative experience a supervisor needs. I remember former Washington (D.C.) Metropolitan Police Chief Chuck Ramsey assigned a young lieutenant named Robert Contee to lead the homicide unit. Contee had no experience investigating homicides, but Chief Ramsey told him that he wasn’t being picked for his knowledge of homicides, he was being picked because he was a good manager. (Contee later became the city’s police chief.)

• Supervisors should ensure that investigators and prosecutors work collaboratively throughout an investigation. Prosecutors determine whether a suspect is charged, and there is a greater chance of a successful outcome when detectives and prosecutors work in close collaboration. And attendees noted that prosecutors often have insights into investigators’ strengths and weaknesses that can be valuable for a supervisor to know.

• The rapid growth of technology has both increased the number of investigative tools to solve cases and increased the workload demands on detectives and the expectations of prosecutors and juries. But technology doesn’t replace the need for more traditional investigative skills. The meeting’s attendees stressed how skills such as conducting witness interviews and area canvases, interrogating suspects, and cultivating informants are important as ever. The challenge for supervisors is to stay up to date on the technologies that could make their detectives more effective. Some emerging technologies, such as artificial intelligence and facial recognition, may help investigators but raise complex policy considerations.

• The staffing shortages that have hit law enforcement agencies across the country have affected investigative units. Supervisors must understand how to use their limited personnel resources most effectively and handle all cases appropriately. The Houston Police Department recently faced a crisis because of its use of the code “Suspended—Lack of Personnel” in its records management system. While this is an extreme example, agencies must consider how they handle the cases they are unable to fully investigate because of limited resources. Creating a clear policy and using case screening tools like solvability factors and checklists promote transparency in decision-making and establish a defensible methodology for why some cases are not investigated.

Jackie Sebire, former superintendent with the Metropolitan Police Service (UK).

I’m grateful to everyone who attended this week’s meeting and to Arnold Ventures for supporting this important work. I left the meeting encouraged by the many thoughtful, driven people working on these challenges, and I’m looking forward to sharing this training curriculum with you in the coming months.

Best,

Chuck