The Efficient and Effective Use of Investigators


The efficient and effective use of detectives and detective resources to investigate criminal offenses is strongly influenced by the policies and practices surrounding case assignment to investigators. By first understanding the nature and effectiveness of investigative operations, a clearer picture of how the assignment of cases affects police outputs and outcomes emerges. In addition, the subsequent understanding that it is not only inefficient, but also ineffective, to assign all unsolved cases to detectives provides practical insight for police administrators to utilize in developing strategies for case assignment polices.

Although variations in activities performed by investigators will be evident across differing departments, Chaiken et al. (1977) found that an approximation of ninety-three percent of investigators' time is spent on activities that are not directly related to solving previously reported crimes, based on the Kansas City Police Department's case assignments. Through an examination of the aforementioned cases, reviews with investigators from other cities, and comparisons to their own study's observational notes, Chaiken et al. (1977) conclude that the aforementioned approximation of time applies to other departments as well. It is therefore imperative to understand what activities comprise the bulk of investigators' time. Roughly forty-five percent of investigators' time is spent on activities such as administrative assignments, traveling, general surveillance, and making speeches, which are not case-specific activities; another twenty-two percent of investigators' time, again roughly estimated, is spent on crimes that are never solved (Chaiken et al., 1977). This leaves an estimated thirty-three percent of investigators' time spent on cases that are solved, but of that total about twenty-six percent is spent on work related to cleared cases after they have been solved, which includes preparing cases for court (Chaiken et al., 1977).

While much of the aforementioned data on the percentages of time investigators spend on certain activities provides insights into potential organizational restructuring and reallocation of duties to increase the effectiveness of detectives, that is beyond the scope of this article; recognizing and understanding that approximately seven percent of investigators' time is spent actually performing investigative work, and that twenty-two percent of their time is spent on cases that go unsolved, clearly illustrates that the structure and determination of case assignments significantly impacts investigators' outputs. Further, a significant amount of the time spent on unsolved crimes could theoretically be reallocated to increasing investigator effectiveness through strategic case assignment practices. Before examining case assignment practices, however, it is necessary to first understand the strongest indicator of whether or not a case will be solved: information.

The availability and reliability of information received by police about incidents and offenders directly impacts the ability of police officers to solve crimes and identify and apprehend those who commit crimes (Skogan and Antunes, 1979). In fact, as cited by Skogan and Antunes (1979), the RAND Corporation concluded an analysis of the criminal investigation process in 1975 with the finding that the information a victim supplies to the responding patrol officer is the single most important determinant of whether a case will be solved; if information that uniquely identifies the offender is not supplied, the likelihood of the perpetrator being identified is reduced exponentially. Brandl and Frank (1994) provide further support for the conclusion that the amount and quality of information available to the police is of paramount importance in their study of burglary and robbery cases assigned to investigators in a Midwestern municipal police department from July 1, 1989 through June 30, 1990, though it should be noted that their study was aimed at identifying the impact of time spent on cases compared to the amount of information available.

Identifying the significant findings of Brandl and Frank’s (1994) analysis plays a key role in understanding how case assignment practices impact the efficiency and effectiveness of investigators, especially when examined in conjunction with Eck’s (1992) triage hypothesis. Eck (1992) posited that cases may be divided into three groups, though the groups most likely represent a range along a continuum: 1) cases that cannot be solved with a reasonable investigative effort, 2) cases solved by circumstance, which only require proper follow-up activities by police, and 3) cases that may be solved with a reasonable investigative effort but that will not be solved otherwise. Combined with Brandl and Frank’s (1994) finding that cases wherein moderate information about a suspect is available the probability of an arrest increased significantly with more investigative time, as well as the finding that investigators spent more time on cases with moderate suspect information available than on cases where information was strong or weak, Eck’s (1992) triage hypothesis provides a solid framework from which case assignment strategies may be devised.

Using Eck’s (1992) triage hypothesis as a guideline, case assignments may be distributed to investigators or specialized teams based on a number of factors: the type of criminal offense, the amount of information available about the perpetrator(s), and whether the specialized knowledge and training of a detective is necessary or if routine follow-up is all that is required to close the case. This not only serves the purpose of increasing efficiency through the reallocation of police resources, such as utilizing clerical support staff in documenting and filing away an unsolvable case, but also significantly increases the effectiveness of investigative personnel by only being assigned cases that possess some measure of potential solvability, except as noted below. Understanding the impact of such a system is best understood through an analysis of Chaiken et al.’s (1977) findings on which actions investigators are typically assigned may be shifted to other personnel.

Patrol officers who are trained as generalist-investigators, according to Chaiken et al. (1977), may be utilized to supplement investigative activities and shift some responsibilities that do not require specialized investigative skills away from detectives, thereby freeing up the time of detectives for devotion to cases wherein some suspect information is known but the case is not solvable without an investment of effort. Such responsibilities would include the apprehension of suspects in cases where the identity of the perpetrator or perpetrators is known at the time of the crime as well as routine investigative actions such as listing stolen automobiles in the “hot car” file, asking victims to look through previously assembled mug shot collections, awaiting calls with further information from the public, and tracing ownership of weapons utilized in crimes; further, for cases where little or no information is available about an offender, generalist-investigators may serve the public relations duty of demonstrating that the police care about the victim and the crime without tying up the time of detectives (Chaiken et al., 1977).

The aforementioned generalist-investigator function would directly relate to Eck’s (1992) triage hypothesis by assigning cases solved by circumstance to support personnel within the police department, allowing the other two groups of cases to be assigned to specialized divisions. One such division, the Major Offenses Unit as defined by Chaiken et al. (1977), would receive all unsolved serious crime cases, both belonging to Eck’s (1992) unsolvable cases group and the solvable with investigative effort group. The assignment of unsolvable cases to a specialized unit may seem counterintuitive, however this would serve the function of ensuring that all major crimes receive attention in an effort to both demonstrate that the police care about those crimes that most severely impact the public, and the assurance that any later leads on unsolved cases that may be discovered through the investigation of other crimes will not be overlooked as a result of separate case assignments among individual investigators.

Finally, using a similar approach as the aforementioned Major Offenses Unit and drawing upon the research of Skogan and Antunes (1979) regarding increasing police productivity, traditional detectives would be assigned to policing teams, additionally comprised of patrol officers and generalist-investigators, who would be responsible for all police activities within a specified geographic area, with the exception of those cases that would be transferred to the Major Offense Unit. These teams would be assigned all non-serious crimes that fall into Eck’s (1992) solvable with investigative effort category, while those crimes that are deemed unsolvable are shifted to clerical support staff for documentation and filing. Naturally some overlap could occur, since the generalist-investigators and patrol officers in these teams would also be working on those cases solvable by circumstance, but this would serve the important responsibility of providing detectives more time to focus on those crimes within their assigned regions that may be solvable with investigative effort.

Although imperfect, the proposed modifications in utilizing detective resources and time, as well as that of support personnel, present a step forward in increasing efficiency and effectiveness, thereby contributing directly to investigators’ outputs. Police administrators seeking to strategically restructure case assignment policies will be well served to utilize Eck’s (1992) triage hypothesis and Brandl and Frank’s (1994) supporting work as a framework from which justification for the reassignment of cases to either support personnel, generalist-investigators, detectives working in policing teams, or a Major Offenses Unit is clearly illustrated.


Brandl, S. and Frank, J. (1994) The Relationship Between Evidence, Detective Effort, and the Disposition of Burglary and Robbery Investigations, American Journal of Police, 13: 149‑168.

Chaiken, J.M., Greenwood, P.W., & Petersilia, J. (1977). The Criminal Investigation Process: A Summary Report, Policy Analysis, 3:187-218.

Eck, J. (1992). “Criminal Investigation” in Donna Hale and Gary Cordner (eds.) What Works in Policing (Cincinnati: Anderson Publishing) pp. 19-34.

Skogan, W. G., and Antunes, G. E. "Information, Apprehension and Deterrence: Exploring the Limits of Police Productivity," in David Bayley (ed.) What Works in Policing. (Cincinnati: Anderson Publishing) Chapter 4, pp. 108-137