Arresting a suspect of any crime is critical because without an arrest, there is little that the courts or correctional systems can do. Court-ordered sanctions or treatments depend on the apprehension and arrest of a suspect. Crimes that go unsolved reflect poorly on the criminal justice system and indicate an inability of the system to achieve the goal of reducing future crime. When the murders of citizens cannot be solved, the problem of uncleared crimes becomes particularly revealing of the criminal justice system’s inability to reduce violent crimes (Wellford and Cronin 1999). Researchers have attempted to explain the difficulties of solving homicides by comparing incident variables of cleared and unsolved homicides. Police administrators have implemented cold case units in their efforts to increase clearance rates.
Clearance Rates
The national clearance rate for homicide, according to the Uniform Crime Reports (UCR), has declined from 94% in 1961 to 64% in 2002 (U.S. Department of Justice 2002). Although UCR rates are not always considered the most dependable measure of crime, they are probably the most dependable for the crime of murder. It is important to recognize that UCR clearance rates are established by dividing the number of homicides by the number of arrests, but also included are murder-suicides and self-defense cases. Including suicides and self-defense cases, in which the offender can be easily identified, lowers the actual clearance rates of homicides.
Variables Affecting Clearance of Homicides
There was little research on the solvability factors of homicide investigations until the early 1990s. Previously, Greenwood, Chaiken, and Petersilia (1977, as cited in Wellford and Cronin 1999) studied outcomes of detectives and questioned their usefulness, but did not study investigative strategies. Keppel and Weis (1994, as cited in Mouzos and Muller 2001) examined the distances between important areas of the crime itself, for example, the point of contact and disposal site, and clearance rate. They concluded that information about the time and location issues increases the crime solvability. Reidel and Rinehart (1996) found that the single most important factor was whether the homicide was related to another crime. If it was committed in connection with such crimes as robbery or rape, it was less likely to be solved than if involving a dispute. It is reasonable to assume that most of these unsolved homicides were committed by strangers or others who had not been directly known by the victims or their associates.
Wellford and Cronin (1999) examined fifty-one characteristics and constructed eight regression models from the significant variables. The offender-victim models disclosed that if the offender was African American and/or the victim had a history of drug use, the solvability increased over the base rate. The computer-check model that included computer checks of the victim, suspect, witnesses, and guns resulted in all four of these variables adding to the increase in solvability. The witness model increased the solvability to 95%, with three of its predictors being significant: witness provided valuable information, friends or acquaintances interviewed, and neighbors interviewed. Crime scene variables that were significant included the notification of the homicide unit, medic, and crime lab by the first officer, the attempt to locate witnesses, and proper crime scene sketch and measurement.
The model that examined detective variables was particularly impressive. Four variables—three or more detectives working the case, arrival by detectives to the crime scene within thirty minutes of being notified, detailed description of the crime scene in detectives’ notes, and following up on all witness information—rated a 96% chance of solving the case. Circumstances such as occurring in a private residence, having an eyewitness to the crime, and not being drug related improved the base rate from 74% to 98%. Of the original fifty-one variables identified as associated with clearance, thirty-seven were associated with police practices rather than the event itself. Wellford and Cronin (1999) found that these variables remained significant across different sizes of cities. These researchers concluded that the practices and policies of law enforcement agencies can impact the clearance rates of homicides.
Although there are differences among homicides and their level of solvability, there is support for the conclusion that the necessary allocation of resources for homicide investigations does increase the probability that cases will be cleared. Mouzos and Muller’s Australian study (2001) supports many of Wellford and Cronin’s findings. They found a few more incident and victim characteristics that made cases less likely to be solved, such as older victims (thirty years or older), working at the time of the incident, lack of alcohol consumption, and occurrence between 6 p.m. and 6 a.m.. They also included the importance of forensic evidence and specialists and modern technology, emphasizing the growing importance of DNA evidence and national databases such as AFIS (Automated Fingerprint
Identification Systems) and CODIS (Combined DNA Index System).
The Implementation of Homicide Cold Case Units
With advanced technology to analyze physical evidence and DNA and fingerprint national databases, there has been an increased interest in old homicide cases that have never been solved. Many police agencies began adding cold case homicide investigators around the year 2000 as advancements in DNA and other forensic technology progressed. A few departments such as the Metropolitan Police Department in Washington, DC, implemented a unit as early as 1992. Utilizing six homicide detectives and eight FBI agents full time, the Metropolitan Police Department closed 157 cold cases within the first five years (Regini 1997).
Making use of other resources, several agencies are teaming with their prosecutors’ offices. Harris County Police in Texas formed a homicide cold case unit that works in conjunction with the division chief of their major offender unit of the district attorney’s office, who prosecutes cold cases exclusively. In Fairfax County, Virginia, the state’s attorney works along with the local police agency’s cold case unit. Other agencies such as Charlotte-Mecklenburg Police Department in North Carolina have included volunteers with previous law enforcement backgrounds. These individuals review case files and meet with designated cold case investigators to help them establish investigative leads (Lord 2005).
Selecting cold cases that have solvability possibilities is critical. Agencies have found that the availability of physical evidence that is conducive to modern technology, of witnesses, and of an identifiable and living suspect are important criteria. The following are two examples of solved cold cases.
After several decades, a skeleton was found, then identified and publicized. After seeing the broadcast of the discovery on America’s Most Wanted, the defendant’s ex-wife came forward to report the murder of a young girl by her then-husband. There was no physical evidence or weapon to link the defendant to the crime; the case revolved around the ex-wife’s testimony. She described how she drove while he attempted sex with and then killed the girl. The defendant was convicted (Lord 2005).
An example of one of many cases in which samples for DNA analysis are submitted to CODIS for comparison was in Iowa, where a suspect was tried in 2003 for the sexual assault and murder of a woman in 1981. The decision to prosecute was first made in 1996 when DNA analysis was conducted on swabs taken at the victim’s autopsy. At that time, the ratio was one in ten thousand chances that the DNA could be from a different individual than the defendant. In 2003, the DNA was reanalyzed, and the chance was increased to one in 100 billion chances of wrong identity. The defendant was convicted (Lord 2005).
There are still several problems in solving cold cases. In the past, technicians and detectives collected evidence based on the analysis that could be conducted at that time. Therefore, evidence that could be analyzed today and would have been helpful in connecting the suspect to the crime scene or the victim may not have been collected. Second, old technologies, such as ABO or enzyme typing, used up a great deal of the evidence in analysis, so often there is little evidence left to analyze with new technologies. Also, the packaging of the evidence in some cases is deteriorating, so the evidence might have become contaminated. In addition, the memory of living witnesses and the admission of previous statements from witnesses who have died can be an issue (Lord 2005).
A large volume of unsolved homicides is a stain on any law enforcement agency’s credibility. Cold case homicide units have caught the imagination of the public, and families of the victims have renewed faith that the murderers of their loved ones will still come to trial.
