(Header: The Oriole Bird and Baltimore Police. Photo credit: Keith Allison // Flickr Creative Commons)
Over the past thirty years, homicide rates have dropped to historic lows nationwide. Yet, the national murder clearance rate—the percent of cases in which the police gathered enough information to make an arrest—has remained at around 64%. Thus, one-third of all murders remain unsolved. Against this trend of fewer murders, a rash of homicides has cropped up in some American cities, while homicide clearance rates go down. For instance, as Chicago’s clearance rate dropped to 20%, its murder rate increased by 59% in 2016. In Baltimore, the murder rate hit record highs, topping Chicago’s per capita.
Many of the homicides in cities like Baltimore are the result of drug and gang violence, which has problematic implications for witness cooperation in police investigations. MIT GOV/LAB investigates the relationships between citizens and government and how trust and compliance, or lack thereof, help or hinder community safety. With seed funding support from GOV/LAB, PhD doctoral candidate Andrew Miller is exploring what motivates citizens to cooperate with state and non-state actors when the two are in competition. These cooperation decisions are relevant to police (state actors) investigations into gang (non-state actors) activity. Why do some citizens with information come forward while others remain silent?
He is testing potential motivators and inhibitors to cooperation such as a sense of moral duty to cooperate and social influences (e.g. seeing other community members cooperate with police motivates citizens to do so themselves). This summer I supported Andrew’s work by researching known factors that affect clearance rates to provide some insight into aspects of Baltimore’s unsolved homicides. To do so, I merged criminal record data from Baltimore city circuit court cases (using common identifiers such as birth dates) with data about the victims of homicide taken from Murder Ink, a Baltimore City Paper column and database.
Factors affecting clearance rates
Despite media coverage of rising murder rates and dropping clearance rates in some American cities, there has been little explanation of why homicide clearance rates are dropping. This dearth of data about why clearance rates are so low in many of these cities prevents municipal governments and police departments from implementing more effective policing and investigative techniques. The citizen compliance project approaches the issue of effective government by investigating the causes of witness cooperation, an important factor that has a significant positive effect on clearance rates (Wellford & Cronin, 2000).
The Justice Research and Statistics Association (JRSA), a Washington based nonprofit, published research on homicide clearance rates, including a 2000 study identifying the factors that impact clearance rates. This study can serve as a baseline for identifying specific clearance rate affecting factors in cities like Baltimore. The JRSA study tested 215 factors that might affect homicide clearance rates. Among the factors that were found to have an effect on clearance rates, two stood out as being most relevant to Baltimore: criminal priors and drugs. If a victim had a past criminal record or if drugs were involved in the homicide (e.g. the homicide occurred during a drug deal, victim was a drug user, victim was a drug deal, etc.), the likelihood of the case being closed decreased significantly. Some factors that positively impact clearance rates include witness cooperation and recovery of the murder weapon (Wellford & Cronin, 2000).
The case of Baltimore
The Baltimore Police Department (BPD) reports a clearance rate of around 50% for 2017—below the national average but on par with other major cities. Half of these clearances were the result of an arrest; the other half were closed for closed for alternative reasons. Many of the cases have been “closed by exception”, meaning that suspects in a homicide case are killed, or other circumstances prevent an arrest from being made (e.g. law enforcement cannot execute a warrant outside of their jurisdiction). Cases closed by exception, along with recently solved homicides that occurred in the previous year, murder-suicides, and justifiable homicides (i.e. self-defense) are all included in this 50% statistic.
The Murder Ink and circuit court data showed familiar patterns on what makes some cases so difficult to solve. The homicide data revealed a roughly 12% lower clearance rate for murder victims with criminal records and those without. Due to the fact that most homicide victims at least had some criminal connection to drugs, there is not enough data to analyze accurately the impact of drug involvement on homicide clearance rates in Baltimore. Nonetheless, the JRSA findings suggest that this high rate of drug involvement in murder cases may play a significant role in lowering clearance rates (Wellford & Cronin, 2000).
While the data is far from conclusive, it does raise the question of why homicide clearance rates are so low. The high rate of drug involvement in homicide cases is likely a consequence of crews vying for control of territory, gangs taking out insubordinate members, and ambitious dealers trying to rise through the ranks by force. When homicides are the result of gang-related violence, witnesses are less likely to come forward and cooperate for fear of violent retribution. This fear is perpetuated by a “stop-snitching culture” that looks down upon cooperation with police and is exacerbated by high-profile cases of misconduct.
The JRSA article provides a framework of potential factors contributing to low homicide clearance rates that, when coupled with in-depth homicide data, can be used to determine specific challenges in police investigation techniques. Using this framework, we have been able to analyze data from Murder Ink and Office of the Public Defender, but more detailed investigation is required to determine the cause of the low rate of homicide clearance. More comprehensive data on Baltimore-specific police investigation practices would need to be collected and analyzed in order to isolate specific challenges or issues in policing techniques. This data, combined with input from affected communities, could be used to inform better policies in investigation and ultimately result in more solved cases.
Nicholas Newton-Cheh (firstname.lastname@example.org) is a Senior at Lexington High School. He is an intern at the GOV/LAB, assisting Andrew Miller on his dissertation research.
Wellford, C. & Cronin J. (2000). “Clearing up homicide clearance rates.” National Institute of Justice Journal 243: 1-7.