Investigative Resources and Crime Clearances: A Group-Based Trajectory Approach

• Author: John L. Worrall
• Published date: 01 March 2019
• Date: 01 March 2019
• DOI: http://doi.org/10.1177/0887403416650251

https://doi.org/10.1177/0887403416650251

Criminal Justice Policy Review

2019, Vol. 30(2) 155 –175

© The Author(s) 2016

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DOI: 10.1177/0887403416650251

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Article

Investigative Resources

and Crime Clearances: A

Group-Based Trajectory

Approach

John L. Worrall1

Abstract

Past studies of crime clearance rates have largely ignored the role of investigators

in the process. This omission is important because criminal investigation is essential

to clearing crimes, particularly those in which offenders are not readily identifiable.

Using data from 570 law enforcement agencies spanning a 13-year period from 2000

to 2012, this study developed group-based trajectories of violent and property crime

clearance rates (an approach not taken in previous clearance rate research), then

modeled group membership with two measures of investigative spending and one

of the proportion of investigators in sampled agencies (“investigative resources”),

while controlling for factors such as workload and crime type. Results from a series

of multinomial regression models suggest investigative resources play only a marginal

role in crime clearance trajectories. This finding is consistent with early detective

research, including the classic RAND criminal investigative process study.

Keywords

group-based trajectory, clearance rate, investigation

Along with crime rates, arrests, citations, and response times, crime clearance rates

(usually defined as offenses cleared by arrest divided by offenses recorded) are used to

measure police performance. For better or worse, police administrators are accountable

to policymakers for them (e.g., Navratil, 2015). The media use clearance rates to rebuke

agencies whose performance falls short of expectations (e.g., Isackson, 2013).

Criminologists have sought to explain them (e.g., Paré, Felson, & Ouimet, 2007). Just

1University of Texas at Dallas, Richardson, TX, USA

Corresponding Author:

John L. Worrall, Criminology Program, University of Texas at Dallas, 800 West Campbell Road, GR 31,

Richardson, TX 75080, USA.

Email: worrall@utdallas.edu

650251CJPXXX10.1177/0887403416650251Criminal Justice Policy ReviewWorrall

research-article2016

156 Criminal Justice Policy Review 30(2)

recently, National Public Radio assembled an online database wherein concerned citi-

zens can readily access crime clearance rates for their own communities (Kaste, 2015a).

Crime clearance rates remain a key indicator of police performance, even despite

awareness of their limitations (discussed further in the Clearance Rates section).

Experts have for years recommended alternatives (e.g., Alpert & Moore, 1993;

Bonkiewicz, 2015; Davis, Ortiz, & Euler, 2015), and some agencies have responded

by measuring police success with increasingly sophisticated methods (e.g., Van Meter,

2001). Nevertheless, clearance rates continue to factor prominently into budgeting and

resource allocation decisions. Indeed, they are arguably more important now than in

points past, as clearance rates have generally been declining at the same time crime

has been declining (Ousey & Lee, 2010). Lackluster clearance rates have suddenly

become conspicuous (Kaste, 2015b).

Nine in 10 homicides were cleared in 1960. Recently, that figure dropped to six in

10 (Kaste, 2015b). The most precipitous—and almost perfectly linear—drop occurred

between 1970 and 2000 (Ousey & Lee, 2010), bucking crime trends in both the “get

tough” era (S. Walker, 1998) and the “great American crime decline” of the 1990s

(Zimring, 2006).

Clearance rates first fell at a time when incarceration was increasing, then they

continued to fall as crime declined in the 1990s. Conventional wisdom suggests at

least some of the imprisonment binge owed to police identifying and arresting more

criminals, but clearance rates did not bear this out. Likewise, it seems plausible that

the 1990s crime drop freed up resources for improved investigations, but clearance

rates continued to slip. One study attributed the drop to “substantial changes in the

nature of homicides, combined with insufficient organizational capacity within the

criminal justice system” (Maguire, King, Johnson, & Katz, 2010, p. 373), but other-

wise this strange pattern remains largely misunderstood.

Explanations for changes in crime clearance rates remain scant and underdevel-

oped. The clearance rate literature pales in comparison with the crime rate literature,

plus it is increasingly dated. The classic RAND Corporation study of detectives

(Greenwood, Chaiken, & Petersilia, 1977), perhaps the most comprehensive to date,

was published nearly 40 years ago. In addition, what little research is available either

explains clearance rates in terms of (a) factors over which the police have almost no

control, or (b) crude metrics that bear little intuitive connection to what crime clear-

ances actually measure. Concerning the former limitation, researchers have explored

the relationship between community size and clearance rates (e.g., Cordner, 1989;

Mesch & Talmud, 1998; Paré et al., 2007), but it is not within police departments’

purview to alter the sizes of their communities. Similarly, researchers have explored

whether community socio-demographic characteristics are associated with clearances

(e.g., Borg & Parker, 2001; Liska & Chamlin, 1984), but police departments are in no

position to alter the demographic composition of their respective communities.

Other studies have turned attention inward toward law enforcement organizations,

exploring the association between crime clearance rates and police-related variables,

including workload (Bayley, 1994; Sullivan, 1985), agency size (Cameron, 1987; Eck

& Maguire, 2000; Levitt, 1997), case type (Cordner, 1989; Mesch & Talmud, 1998;