THE NEW DETECTIVE
The new detective
Rethinking criminal investigations
John E. Eck1,∗D. Kim Rossmo2
1University of Cincinnati
2Texas State University
John E. Eck, School of Criminal Justice, The
University of Cincinnati, P.O. Box 210389,
Cincinnati, OH 45221-0389.
∗Order of authorship was determined by a coin
Wet hank Gary Cordner forshar ing his archive
of old documents from the Uniform Crime
Reporting program and the reviewers and
editors for their useful and insightful comments
that improved our article.
Research Summary: The clearance rates for murder and
other serious crimes have declined significantly for almost
60 years despite significant technological improvements
in police investigations. The reasons for this are not well
understood. We argue here for rethinking why, what,
and how police investigators operate so as to repurpose
their work for reducing crime. These changes include
improved thinking by detectives to reduce investigative
errors, increased focus on patterns of crimes, and better use
of detective expertise in crime prevention.
Policy Implications: First, police should work to reduce
investigative failures by improving investigative thinking.
Second, tinkering with the administrative practices of
investigative units seems unlikely to produce significant
results. Third, police agencies should engage detectives in
crime prevention. Finally, police agencies should connect
investigations to problem solving.
clearance rates, crime prevention, criminal investigations, detectives,
police problem solving
In the popular imagination, police investigators have a great deal of status. From Dragnet to The Wire to
CSI to True Detective, most television police shows are about plainclothes investigators. Detective work
has long been considered critical to the police function, and even though they are fewer in number than
patrol officers, detectives make up for their minority standing by their elite status. So, it may come as a
surprise to most of the public (and their chronically oblivious elected representatives) to learn that the
contributions of criminal investigations to public safety have been difficult to measure and establish.
Researchers in the 1970s and 1980s found that investigators solved only a small proportion of the
Criminology & Public Policy. 2019;1–22. wileyonlinelibrary.com/journal/capp © 2019 American Society of Criminology 1
2ECK AND ROSSMO
crimes assigned to them, and those they did solve were most often brought to successful conclusions
through statements from victims and witnesses and by the initial efforts of patrol officers (Eck, 1983;
Greenberg, Elliott, Kraft, & Proctor, 1975; Greenberg, Yu, & Lang, 1973; Greenwood, Chaiken, &
Things have not improved. Indeed, they have worsened. The solution rates for most crimes have
fallen for almost 60 years, a period that has had considerable improvement in investigative technol-
ogy (Federal Bureau of Investigation [FBI], 2017). Police reform efforts during this time emphasized
patrol work and mostly ignored investigations. The attention of new policing strategies advocated
by reformers—community policing, broken windows, hot-spots patrols, and even problem-oriented
policing—was concentrated on uniformed officers. If investigations were mentioned, it was usually in
a secondary and supporting role.
In this article, we depart from the standard approach researchers have taken to the criminal inves-
tigations function. In previous studies, researchers have focused on investigative results, in particular,
on the solution of individual crimes. Although solving crimes is important, this result is not the only
one we want. Criminal investigation operations should be aimed at two different outcomes. The first is
the promotion of justice. The second is the reduction of crime. Solving crimes is a means to both these
ends. The evidence to date, however, indicates that solving more crimes has a limited potential for
achieving either outcome. Moreover, if managers overemphasize crime clearances, they may under-
mine justice. We argue that criminal investigations should (a) focus on the quality of investigations
by aiming to reduce errors and (b) orient investigative units toward prevention as well as toward the
solution of crime.
This summary of our argument may seem counterintuitive or even mistaken. To demonstrate why
our position is sensible, we look at the research on the investigative function and the evidence sup-
porting the intuitive appeal of assuming increased solution rates reduce crime. We suggest that during
the last third of a century, criminal investigations have become a backwater in police improvement
efforts; the lion’s share of the theorizing, research, and action has been focused on the patrol function.
Much has been learned from these successful efforts. To improve the criminal investigations function,
investigative managers, police leaders, and politicians need to draw on the lessons that helped improve
policing overall. It is time investigations were brought from the 1950s into the twenty-first century. We
offer a broad set of policy recommendations to do this.
Our article is organized as follows. We first describe the drop in solution rates for serious crime in
the United States over the last 50 years. Although it is a crude measure, the figures reveal that despite
developments in investigative technology, and improvements in overall police effectiveness, solving
crimes has regressed. In the second section, we discuss the research on investigative activities and why
the focus on solving crimes is probably misguided. Despite our discomfort with measuring detective
performance with solution rates, the investigation of crime is important to policing and society. We
debate why we need investigations in the third section. If investigations are important but the focus
on solution rates is misguided, how can investigations operations be improved? In the fourth section,
we point to the fact that the patrol function has improved its effectiveness by dealing with crime
patterns rather than with singular events, but the investigations function has generally not learned this
lesson. In the penultimate section, we describe three broad thrusts for investigations improvement:
(1) focus on quality and reducing errors; (2) organizing investigators so they can take advantage of
repeat offending, repeat victimization, and repeat crime places; and (3) involving detectives directly
in crime prevention. We end the article by summarizing the argument, reviewing our recommenda-
tions, and calling for police–researcher collaborations to explore further how investigations can be
ECK AND ROSSMO 3
FIGURE 1 Clearance rates and crime rates for violent crime, 1960—2017
1THE WORSENING PROSPECTS FOR SOLVING CRIMES
If investigations made the public safer, then increases in solution rates would be associated with drop-
ping crime, and decreases in solution rates would be associated with crime increases. If the ability
of detectives1to solve crimes is impeded by high crime levels, then when crime drops, their solution
rates should improve. Over time, as police have employed increasingly sophisticated technology—
DNA analysis, automated fingerprint identification, multiple linked computer databases, closed-circuit
television recordings, and more—we would expect to see greater success at solving crimes and a rise
in solution rates.
It turns out that these hypotheses are as realistic as the aforementioned television police shows.
Figures 1 and 2 show the relationship between crime clearance rates (the indicator of solutions consis-
tently measured by the FBI) and crime rates over 58 years, from 1960 through 2017. Figure 1 charts
four violent crimes. In each case, clearance rates decline. Although police had decreasing success at
discovering who committed violent crimes during this period, the crime rates went up and then down.
The homicide solution rate is much like the trends in solution rates to other crimes. The reasons are not
known even though proposed causes include the changing nature of murder (more stranger crimes),
police resource limitations, declining community support, a greater tolerance for violence, and more
legal regulation (Braga & Dusseault, 2018).
As crime dropped from 1991 on, it is particularly notable that clearance rates also dropped, with the
possible exception of those for robbery. It is hard to make a case that improvements in investigations
contributed to the drop in violent crime or that the decreasing volume of violence since 1990 helped
improve investigations. In short, if police practices contributed to the dramatic drop in violent crime
since 1990, the changes that made this contribution probably had little to do with investigations.
Figure 2 shows similar trends for the three serious property crimes consistently tracked by the FBI.
Burglary and motor vehicle theft had far higher solution rates in 1960 than they did in 2017. Only
larceny-theft bucks these trends, but it started in the 1960s with the lowest clearance rate of the seven
crimes examined and then bounced up and down, never rising above 23%.2Like violent crime, property
crime went up in the 1960s and 1970s and then declined in the 1990s through the end of the series. So,
4ECK AND ROSSMO
FIGURE 2 Clearance rates and crime rates for property crime, 1960—2017
again, it is hard to credit improvements in public safety to investigations, and it seems declines in the
crime rate did not help police solve property offenses.
Several caveats need to be kept firmly in mind when interpreting these statistics. First, for several
reasons, clearance rates are not great measures of investigative success. Although the FBI provides
rules for classifying a crime as cleared, this can happen even if a suspect has not been arrested. This
makes sense if the suspect is dead or already incarcerated. But police agencies have been known to clear
crimes with weak evidence; their willingness to do so varies across police agencies (Eck, 1983) and
over time. If police agencies were casual about what they called an investigative success in the 1960s
and then tightened their criteria during the police reform movements of the 1970s through 1990s, this
might account for some of the decline in clearance rates. In other words, the high clearance rates early
in this 58-year time series could have been exaggerated and more recent clearance statistics might be
Second, police may have become much more diligent in following constitutional safeguards. The
high solution rate for murder in 1960 could contain many more innocent (and constitutionally not
guilty) arrestees than the lower solution rates later. There is no good way to know, but given the number
of people found to have been falsely convicted of murder, we cannot rule out the possibility that the
higher solution rates of yesteryear were at least slightly inflated by wrongful arrests.
Third, many crimes are solved by patrol officers before detectives get involved. For examples, an
officer discovers a burglary in progress and arrests the miscreant; responding to a domestic violence
case, the officer arrests the assaulter; or a store clerk detains a shoplifter and calls the police.3
Finally, clearance rates are calculated by dividing the number of crimes solved in a year by the
number of crimes occurring that year. So, a burglary occurring in 2010 that was not solved until 2011
decreases the clearance rate for 2010 but increases the rate for 2011. If in the late 1990s and early 2000s
police reexamined cold murder cases and solved some of them, these solutions add to the clearance rate
for the year of the solution even though they do not pertain to murders occurring that year. Over time,
this might not make much difference, but we cannot be sure and it does confuse our understanding.
These trends cannot be used to support the notion that police have become better at solving crimes
over the last 50 years. In 2016, the national murder clearance rate in the United States dropped to a
ECK AND ROSSMO 5
historic low of 59% (FBI, 2017). Thus, a daily average of 19 murders across the country will not be
solved. In some major cities, the arrest rate is now as low as one in four murders (Kelly, Lowery, &
2WHAT POLICE INVESTIGATORS DO
The criminal investigation function remains rooted in the professional police model of the mid-
twentieth century (Braga, Flynn, Kelling, & Cole, 2011). Despite significant technological advances
in forensics and information systems, there has been little experimentation or innovation in the inves-
tigation process itself. Detective work is typically reactive, initiated by the report of the commission
of a crime. Most arrests are made by patrol officers on the basis of information from the community
(Greenberg et al., 1975; Greenberg et al., 1973). The primary goals of crime solving remain justice,
deterrence, and offender incapacitation.
The public perception of police detectives is mainly driven by television and popular fiction. But the
reality is much different. Although research on the investigative function is limited, the RAND study of
detectives conducted in the mid-1970s (Greenwood & Petersilia, 1975) and a 25-year follow-up survey
of national police investigative policies and practices (Horvath, Meesig, & Hyeock Lee, 2003) provide
Despite the detective mystique, most crimes are solved by members of the public,4then by patrol
officers, and last by detectives. In retrospect, this is not surprising; there are many more people in the
community than police officers, and many more patrol officers on the street than detectives. Clear-
ances are typically the result of on-scene arrests, the initial identification of suspects by victims and
witnesses, or forensic evidence. Consequently, detectives invest more effort in collecting evidence for
a prosecution than in trying to identify unknown criminals.
Police investigators spend much of their time engaged in administrative functions such as reviewing
reports, finding/interviewing witnesses, and file documentation. For those cases that are solved, it
takes less time to identify the offender than to complete the post-clearance processing. Detectives
seriously examine a minority of reported crimes, dealing with most in less than a day (Eck, 1983).
Only a few crime scenes are processed for physical evidence; even for those that are, not all available
evidence is recovered (Eck, 1983), and recovered evidence is unlikely to be used to identify a suspect
(Peterson, Sommers, Baskin, & Johnson, 2010). The potential of crime scene forensics for solving
crimes is undermined if the police agency’s evidence processing capabilities cannot effectively handle
the demand. Anderson, Matthies, Greathouse, and Chari (2018) recently found that the full potential
of forensic science in criminal investigations remains unrealized. Evidence is analyzed in only a small
percentage of cases, and it occurs more commonly for case building after an arrest rather than as a
means of identifying the offender. Long turnaround times are a problem, in particular, for less serious
Horvath and colleagues (2003) found that investigations managers did not fully understand their
function and often knew little about the nature or effectiveness of their operations. The main reasons
proposed by police agencies for a decline in serious crime clearance rates were too many crimes, a
lack of time, witness cooperation problems, and charge reluctance by prosecutors. More personnel,
increases in training, and advances in technology were seen as necessary to increase clearance rates;
training in particular was noted as being “inadequate, inconsistent and incomplete” (p. 6). The expla-
nations of too many crimes and a lack of time, however, are not supported by the recent crime drop.
Witness cooperation problems circle back to the public. Finally, technological improvements over the
last couple of decades have not had a measurable impact on crime clearance rates. Horvath et al. (2003)
6ECK AND ROSSMO
warned that technology can only play a supportive role, one that depends on the nature and quality of
the police–community relationship.
Police agencies tend to focus on case clearance rates and typically use this measure as a means
for evaluating detectives. RAND, however, determined this was not a suitable method for comparing
inter- or intra-agency investigative effectiveness because of calculation inconsistencies. Organizational
behaviors can evolve into automatic processes (Allison & Zelikow, 1999), resulting in the mindless
pursuit of performance metrics at the expense of the real purpose of the agency’s mission. As Good-
hart’s law warns, “When a measure becomes a target, it ceases to be a good measure” (Strathern, 1997,
Detectives sometimes fall victim to the current “quick fix,” a trap that typically involves detectives
waiting for something to happen—a witness to walk in, the Crime Stoppers phone to ring, the DNA
results to come back. This is problematic for several reasons. First, a good detective should use all the
relevant tools in his or her toolkit. Second, time is often a critical factor in an investigation, and unnec-
essary waiting may result in the loss or deterioration of valuable evidence. Third, such an approach
eventually leads to detectives implicitly learning that particular techniques solve crimes. If these tech-
niques are not productive, detectives may then assume nothing more can reasonably be done on the
case. This lesson is wrong: Crimes are solved by people, not by tools.
The potential for increasing police clearance rates has been questioned. “It is unlikely that improve-
ments in the way investigations are conducted or managed have a dramatic effect on crime or criminal
justice” (Eck, 1992, p. 33). Not all murders can be solved; police have no control over the killer’s mis-
takes, location of the crime, presence of forensic evidence, existence of witnesses, or the nature of the
victim–offender relationship (Wellford & Cronin, 2000). Unsolvable murders, however, are probably
in the minority and more homicides might be cleared with the proper approach. We argue here that
to improve police investigations, increase solutions, and obtain the most value from detectives, police
need to shift how they think about investigations: what detectives should do and how they should do
it. Rethinking investigations requires us to begin with the reasons for investigations.
3WHY WE NEED POLICE INVESTIGATIONS
We need police to investigate crimes for three reasons. First, to advance justice, police must make
some effort to detect offenders, and the more serious the crime, the more this is necessary. The jus-
tice function is critical even if it makes no contribution to crime prevention. Consider this recent
In April 2018, police in California arrested Joseph DeAngelo, suspected of being the Golden State
Killer responsible for at least 12 murders, 50 rapes, and 120 burglaries from 1974 through 1986. At
the time of his arrest, he was 72 years old and there were no reports he had committed a serious crime
since the middle 1980s (Serna, Winton, Parvini, Mason, & Myers, 2018). Consequently, it is highly
unlikely that his capture and prosecution will save lives. Yet, solving these murders with an arrest is
important. It is important for justice.
The popularity of detective television shows and movies hinges on people’s desire to see good
triumph over evil. Although real investigators are rarely as effective at solving crimes as fictional
characters, governments still need to provide this function, flawed as it may be. Discouraging
vigilantism and preventing private dispensations of justice are important for social order (Leovy,
2015). A police investigation also signals concern, which may be just as important as an arrest in the
wake of a traumatic crime. Tightly coupled with these rationales is the necessity to make the right
people accountable. Justice cannot simply be measured by the quantity of arrests for crimes. We must
ECK AND ROSSMO 7
ensure that those arrested are truly culpable. Reducing investigative errors, therefore, should be a part
of any effort to improve investigations.
The second reason we need police investigations is to maintain a base-level deterrent threat and
incapacitation effect. Given the generally low clearance rates for most crimes, police scholars have
debated the level of deterrence produced by criminal investigations (see Kleck, 2016; Nagin, Solow,
& Lum, 2015).5The cumulative effect of modest risks can be appreciated from the experiences of the
Royal Canadian Air Force in World War II. From March 1943 through February 1944, bomber crews
for the RCAF had an average loss rate of slightly more than 6% on their missions. Consequently, a
crew member’s chance of surviving his 30-mission tour was approximately 16% (Bomber Command
Museum of Canada, 2018). Although the risk of arrest for a given crime is not high, the probability of
eventually being caught is significant for those who continually offend.6This may be where the bulk
of the deterrent effect lies.
A police department’s homicide clearance rate may, therefore, have little impact on the incidence
of murder as most people are not serial killers. The arrest rate, however, could have a strong influence
on common crimes, such as burglary or auto theft. Fear of being caught forces offenders to be more
careful, selective, and less active. Fear might not scare many offenders into stopping, but it probably
does have an influence on their rate of offending. And investigations leading to the imprisonment of
active offenders likely have a nontrivial impact on crime.
Our point hinges on the difference between the absolute solution rate and marginal changes in that
rate. The absolute rate is compared with not solving any crimes, whereas the marginal rate is the dif-
ference between the solution rate at one time and the next. Investigations management and technology
improvements typically influence only the marginal rate. As long as the absolute solution rate is above
a particular level, marginal changes may not make a noticeable difference. So even if marginal improve-
ments in investigations are unlikely to affect crime rates, substantial changes in investigation resources
make little sense.
Although the first two reasons for investigations are obvious, the third is less so. Anyone who has
spent time with experienced police detectives realizes they have a wealth of information about how
crimes are committed and in what circumstances. Investigators apply some of this knowledge to solve
crimes, but much is not put to use because it does not identify offenders or help prosecute them. Their
knowledge, nevertheless, is intelligence concerning criminal behavior. And it is intelligence that could
help craft prevention efforts (Boba & Santos, 2015). Consequently, detectives may be grossly under-
valued and have greater potential for crime control than is generally recognized (Braga et al., 2011).
This raises the question of how police organizations can tap this reservoir of experience and put it to
use preventing crimes.
In the 1970s, the U.S. Department of Justice developed a technical assistance program known as
Managing Criminal Investigations (MCI; Cawley et al., 1977). The program called on police to tweak
their investigations’ administrative practices. So it is not surprising that, even if MCI had been widely
and fully implemented, its marginal improvements would have had little discernable impact on inves-
tigation outcomes. Forty years later, we need to do better. The question is, how? The first step might
be to take stock of how police patrolling improved its effectiveness.
4WHAT INVESTIGATIONS CAN LEARN FROM THE REST
Detective work has been mostly unaffected by changes in modern policing despite evidence that these
reforms had an important role in reducing crime (National Academies of Sciences, Engineering, and
8ECK AND ROSSMO
Medicine, 2018; Sherman, 2013; Weisburd & Braga, 2019; Weisburd & Eck, 2004). Improvements in
police effectiveness came about for many reasons, including greater use of data and analysis. These
were substantial changes that required reimagining the patrol function rather than making marginal
changes, such as reducing response times. Fundamentally, the police agencies that became effective
did so by recognizing that crime has patterns, these patterns give clues to potential interventions, and
if these interventions are applied, they can reduce crime. Crime is not arbitrarily scattered through-
out neighborhoods. It is concentrated in tiny areas. Crime does not occur evenly throughout the day
or week. It is concentrated at specific times and days. Offenders do not operate singly but are often
embedded in networks of offenders. Analytical techniques used by police have helped to identify these
patterns, focus their efforts, and block crime opportunities. Rather than viewing the patrol mission as
running from call to call, astute police leaders realized they could reduce crime by focusing on patterns.
In short, this revolution in policing was based on this recognition of patterns and the change of mission
from call handling only to one that also includes crime prevention.
Detective managers mostly did not get these messages. Horvath et al. (2003, p. 5) found that “the
police criminal investigation process has remained relatively unaffected by the significant changes that
have occurred in policing, the crime problem and technology in the past thirty years.” They specifically
mentioned the isolation of the process from community policing and crime prevention initiatives (see
also Eck, 1983). Police agencies tend to be more concerned with internal organizational issues than
with improving communication and relationships with the community (the major source of crime-
solving information), or in developing more effective working connections between detectives and
patrol officers (the agency’s most important intermediaries with the public).
We do not know why most police reformers ignored the investigative function. Perhaps it was a
wise strategic choice: It was better to have patrol prevent a crime than to increase the chances of detec-
tives solving it. Or perhaps seeking solutions to investigative ineffectiveness was less straightforward
than finding answers to other police problems.7Or perhaps police managers, dazzled by technology,
believed they had implemented improvements to investigations. One thing we do know is the research
that led to improved police effectiveness was focused on patrol and not on investigative activities. To
the extent that this research was aimed at addressing investigations—for example, under focused deter-
rence (Kennedy, Braga, Piehl, & Waring, 2001)—investigators were simply asked to continue doing
what they had always done but to coordinate with other police units.
So, although police patrols were becoming more focused on crime concentrations and patrol officers
and supervisors undertook problem-solving activities, investigators still treated crimes in isolation and
their units’ mission remained limited to solving them. To the extent prevention investigations were
considered, it was to lament the lack of resources. In her excellent book on murder investigations,
Ghettoside, Jill Leovy (2015) repeatedly asserts that there would be fewer homicides if the Los Angeles
Police Department invested more resources in homicide investigation. There is a certain logic to this: If
no killings were investigated, it seems likely that there would be more killings. And clearly, the arrest
of an active serial offender can prevent future crimes by that villain.
This argument is shaky, however. Patrol officers could argue that if they never answered a police
call, crimes would increase. And such a claim would also be valid. But patrol has learned that simply
responding to more calls faster does little. Similarly, if there were no police, we would expect far more
crime than we have now. But this does not mean adding police to our current levels will significantly
reduce crime; the evidence shows that it does not (Lee, Eck, & Corsaro, 2016). In the same way,
marginal improvements in investigations are unlikely to reduce crime in any meaningful way. What is
needed is a shift in investigative strategy: a shift in mission to prevention and a focus on patterns to
achieve this mission.
ECK AND ROSSMO 9
5WHAT DETECTIVES SHOULD DO
5.1 Improve investigative thinking
Most of the proposals made for improving police investigations can be grouped into four cate-
gories: (1) model procedures; (2) additional resources (personnel, forensics, information management);
(3) improved relationships (internal and external); and (4) better training (see reviews in Braga &
Dusseault, 2018; Braga et al., 2011; Riedel, 1995; Wellford & Cronin, 2000). Although these ideas are
all valuable, they overlook a critical factor related to the essence of the detective function—investigative
thinking. Police investigations are about solving crimes, and detectives need to be skilled in deductive,
inductive, and abductive reasoning, not just in the operations of police bureaucratic processes (Fahsing
& Ask, 2018). Determining the truth (or at least the most probable truth given the available evidence)
is a requisite antecedent for justice.
One way to approach the question of how detectives should think is by examining how they should
not think. The study of criminal investigative failures provides some insight into what can go wrong.
Following a medical analogy, a criminal investigative failure is a wrongful conviction (misdiagnosis),
an unsolved crime that should have been solved (unsuccessful treatment), or an ignored crime (failure
We do not know, given sufficient investigative effort, resources, and expertise, how many uncleared
crimes are potentially solvable (unsuccessful treatments). In several studies, however, scholars have
attempted to determine the frequency of wrongful convictions (misdiagnoses). An examination of bio-
logical evidence from sexual assault and homicide cases in Virginia determined new DNA testing
seemed to eliminate the convicted offender in 5% of cases; for sexual assault convictions alone, the
elimination rate was 8% to 15% (Roman, Walsh, Lachman, & Yahner, 2012). Gross, O’Brien, Hu,
and Kennedy (2014) calculated that 4.1% of defendants sentenced to death will eventually be exoner-
ated. Using self-reported innocence claims by state prisoners in noncapital cases, Loeffler, Hyatt, and
Ridgeway (2018) estimated a wrongful conviction rate of 6%.
A wrongful conviction is a wrongful arrest that has, despite the efforts of defense counsel, somehow
passed the scrutiny of first the prosecutor and then the judge and jury. By contrast, the process by which
a solvable crime becomes uncleared lacks any checks or balances and typically involves the decision
of only a single police detective. As a consequence, it does not seem unreasonable to conclude that the
proportion of such crimes considerably exceeds 5%.
Rossmo and Pollock (2019) studied the causes of criminal investigative failures in an effort to
identify their systemic nature and develop a more comprehensive understanding of how they occur.
They classified causes using a scheme for error analysis adapted from Reason’s (1990) failure domains:
(a) personal issues; (b) organizational problems; and (c) situational features. Personal issues were
individual-level problems, such as poor decision-making or flawed judgment (e.g., confirmation bias,
misfeasance). Organizational problems were located in the structure, procedures, training, or resources
of the police agency (e.g., groupthink, poor supervision). Situational factors were environmental
features or characteristics of the crime, external to the control of the police or government (e.g.,
stranger crime, media frenzy). Personal factors, in particular, a rush to judgment, tunnel vision,
and confirmation bias, were found to be the most common causes (61%) of criminal investigative
A crime can only be solved through evidence: a witness, a confession, or physical evidence (Klockars
& Mastrofski, 1991). An unsolved crime, or an incorrectly solved crime (wrongful conviction), is
therefore fundamentally a failure of evidence—its collection, evaluation, or analysis. Evidence collec-
tion involves locating eyewitnesses, interviewing people, recovering physical evidence from the crime
10 ECK AND ROSSMO
scene, and similar efforts. Evaluating evidence is the determination of its accuracy or truthfulness.
Analysis includes extracting information from the evidence, determining relationships, and develop-
ing patterns (Rossmo, 2016).
Most recommendations for improving criminal investigations have involved efforts to increase evi-
dence collection or forensic testing. For example, a recent initiative by the Boston Police Department
to increase its homicide clearance rate was focused on helping detectives find cooperative witnesses,
collect more physical evidence, and conduct additional forensic testing (Braga & Dusseault, 2018).
Evidence evaluation and analysis issues, however, are the more common causes of investigative fail-
ure; Rossmo and Pollock (2019) found breakdowns in evidence collection were much less important
unless they co-occurred with evaluation and/or analysis problems.
Although detectives typically have a good appreciation of the technical nature of evidence, they
do not always fully understand its probabilistic structure (Robertson & Vignaux, 1995). Evidence has
both significance and reliability. Significance is defined as the ratio of the probability of the evidence
given the suspect’s guilt to the probability of the evidence given the suspect’s innocence. It is therefore
necessary to determine not only how strongly the evidence supports the guilt of a suspect or points
toward a particular theory of the crime but also the viability of other explanations for the evidence.
Reliability is the accuracy or truthfulness of the evidence. Evidence must be evaluated to determine
the likelihood that it is true or accurate. All evidence has an error rate: An eyewitness might misidentify
a suspect, a person may make a false confession, or a scientific test can produce a false positive.
Unfortunately, we tend to place more importance on significant evidence even if its reliability is low
(Griffith & Tversky, 2004). Low reliability, however, undermines significance strength; detectives first
need to estimate the reliability of an item of evidence before determining how much weight it should
be given. As the possibility of mistakes and human error always exists, source reliability, forensic
test error rates, evidentiary consistency/trustworthiness data, and any other known issues should be
considered. Evidence is not more reliable simply because the investigator wants it to be, and is not
less reliable because it is inconsistent with the prevailing investigative theory. Cognitive biases lead to
inaccurate evidence evaluation and may result in unsolved crimes or wrongful convictions. Rossmo and
Pollock (2019) found evidence evaluation problems in 92% of the criminal investigative failures they
Given the primary role of evidence, detectives should develop a better understanding of its meaning
and probabilistic structure.8Such an understanding must consider both evidence significance and reli-
ability, and it must explicitly involve the comparison of alternative explanations to avoid the risks of
confirmation bias (see Rossmo, 2009). To obtain a sense of the probative value of an item of evidence,9
detectives need to consider questions of significance, reliability, independence, and patterns (SRIP):
1. What is the significance of the evidence? How strongly does it point toward the guilt of a suspect
or a particular theory of the crime in comparison with other suspects or theories?
2. What is the reliability of this evidence? How accurate or truthful is it? Even if the evidence is
significant, it will have little probative value if it is wrong.
3. How independent is the evidence? Does it provide a unique contribution, or is it merely derivative
of already existing evidence? Evidence that lacks independence may not contribute any additional
information to an investigation.
4. How does the evidence fit in with what else is known in the investigation, its overall information
pattern? Evidence in an investigation should not be cherry-picked but must be considered in a holis-
tic fashion. Different items of evidence may point the investigation in various directions, and these
inconsistencies must be considered and reasoned through.
ECK AND ROSSMO 11
It will rarely be possible to determine precise values here. Rather, the point is to go through the exer-
cise of considering these key questions and thinking about their answers. Much can be gained by using
an ordinal scale and simply getting into the general ballpark (e.g., “very significant,” “unreliable”).10
Danger arises when one of the four SRIP questions is ignored because an investigator suffers from cog-
nitive bias. By asking these questions, and considering their answers, detectives may avoid the more
egregious evidence errors and reduce the risk of a criminal investigative failure.
Awareness of cognitive biases makes them no less easy to avoid, so organizational policies and
procedures are also necessary to control investigative thinking errors (Heuer, 1999). One of the more
effective is the use of external reviewers. In England, an unsolved murder is reviewed at certain time
periods (28 days, 12 months) by an independent detective; in complex or sensitive cases, this person
may be from a different police agency (Association of Chief Police Officers [ACPO], 2006; Jones,
Grieve, & Milne, 2008). Because external reviewers were not involved in the original investigation,
they are in a better position to catch mistakes and oversights and are more likely to point them out.
5.2 Improve investigative results
We are skeptical about the ability of managerial improvements to contribute greatly to crime reduction.
In those police agencies where investigations are poorly managed, understaffed, or badly trained, such
improvements are necessary and likely to be useful. When detective units are operating in the range of
standard competence, however, focusing on modest improvements in managing criminal investigations
is unlikely to make much difference in solution rates. Even if they produce small statistically significant
increases in arrest rates, these are unlikely to have much impact on public safety.
The reason is simple: Offenders usually do not want to get caught, so they undertake counter-
investigation tactics that make identification difficult and uncertain. These include hiding their actions,
leaving less evidence behind, and intimidating witnesses. It is difficult to solve a crime if there is little
evidence available when patrol officers arrive on the scene. If the crime is serious (e.g., a murder), and
is deemed worth investing resources in, a solution is more likely. Even for homicide, however, solution
rates have been declining for decades.
The emphasis on solution rates, whether measured by crime clearances or arrests, is probably an
obstacle to improving the utility of investigations. Clearances are used as a means of scoring internal
agency report cards. Convictions, which are more oriented to crime control (Braga & Dusseault, 2018),
are still only a system product. These metrics are an impediment to success for two reasons. First, as
implied in the previous section, they emphasize quantity over quality and can lead to serious mistakes.
Second, these so-called performance measures focus detective efforts on individual cases and keep
investigators from looking for patterns and from developing contacts within offender communities that
could help them target their resources more effectively. This is much like focusing patrol officers on
rapid response to all calls for service and measuring their productivity by the number of calls handled.
The research findings on investigations are definitive about what leads to crime solutions: It is primarily
information originating from victims and witnesses. Given that the public is so important for case
resolution, any efforts to improve investigatory success—whether to further justice or to prevent future
crimes—must start with the public.
Interestingly, some of the first attempts by the police to improve investigations involved enhancing
contact between detectives and community members, as well as between patrol officers and detectives.
Team policing was a precursor to what we call community policing. It involved decentralizing police
operations, including detectives, to district stations. This brought formerly isolated detectives into rou-
tine contact with patrol officers whose work is vital to investigative success, and it put them closer to
community members (Sherman, Milton, & Kelley, 1973).
12 ECK AND ROSSMO
Some of the lessons learned from team policing may be important today. If the objective is to improve
investigative results, then detectives need to cultivate enduring useful relationships with the people
who are most likely to provide helpful information—those who stand the greatest chance of becoming a
victim and those who may know something about active criminal behavior, including offenders. Repeat
victimization is common, so ∼10% of victims account for close to 40% of all criminal victimizations
(O, Martinez, Lee, & Eck, 2017). Building relationships with victims could aid in solving crimes, if
not the crime immediately reported, then crimes that might be perpetrated against these people later.
Repeat offending is common, too (Martinez, Lee, Eck, & O, 2017), and having a working relationship
with criminals can also be useful. Finally, crimes tend to cluster at the same places—on the same street
segment or at the same address (Lee, Eck, O, & Martinez, 2017)—so knowing the people at these
locations will likely produce more successful investigations.
If detectives are to become more familiar with the people they will deal with in future crimes, their
productivity cannot be wholly measured by clearance rates or similar metrics. More of their time may
need to be spent on seemingly unproductive tasks, unrelated to any specific crime. The ultimate goals
of an investigation are justice and crime prevention. Priorities should thus be based on community
needs, rather than on media, political, or bureaucratic demands.
5.3 Improve detectives’ effectiveness at crime reduction
At the broadest level, the connection between crime solution rates and crime rates is tenuous at best.
We saw this in Figures 1 and 2. This 10,000-meter view, however, overlooks small but significant
contributions to prevention. It is hard to imagine that arresting an active prolific offender does not
prevent the crimes he or she would have otherwise committed. What the macro view does indicate,
however, is that focusing on solution rates in general will make little or no difference in overall crime
rates, and it indicates that adding substantially more resources to investigations to boost solution
rates will probably not help reduce crime in a measurable way. Means of tapping the expertise of
detectives exist, however, that could enhance their contributions to crime prevention. One of the
most promising involves the consideration of crimes as part of a larger pattern rather than as singular
Police organizations in general need to understand the nature of crime better, and investigators
specifically need to develop a greater concern with the circumstances that generate the specific offenses
they handle. Most detective units deal with crime reports in a manner not unlike a manufacturing assem-
bly line (Greenwood, Chaiken, Petersilia, & Prusoff, 1975). A new report comes into the office, and
a supervisor assigns it to the next detective on the rotation. An assignment to investigate a specific
offense, and only that offense, undermines the responsibility for pattern detection, and typically little
formal effort is invested here. Does this new crime connect to other crimes? Is it part of a series of
offenses committed by a prolific offender? Is the crime a product of a problem place, bar, or business?
What social, psychological, geographic, and historic factors underlie this crime?
We suggest detectives would be more effective in disrupting criminogenic situations and preventing
crimes if they made a greater effort to understand their underlying patterns. We can learn from the
medical model of treatment and prevention; a good doctor is expected to diagnose the cause of a sick-
ness, treat the symptoms, cure the disease, and provide advice for future prevention. Some detectives
in some agencies do some of this some of the time, but it is not standard business.
Determining the investigative target requires an understanding of the underlying crime patterns.
Patterns can be offender based or situation based. Offender-based patterns involve both serial crime
and gang problems. Traditionally, police have been more attentive to the latter than to the former.
Much could be gained, however, from crime linkage analysis (Rossmo, 2000). Knowing the extent of
ECK AND ROSSMO 13
the offense pattern establishes the dangerousness of the offender and the appropriate level of police
response. It facilitates information sharing among investigators and between jurisdictions. A more
comprehensive picture of the offender can be formed, and common suspects can be identified. Finally,
if the case is solved, additional crimes can be cleared and a more appropriate court sentence can be
A substantial body of research consistently confirms a minority of offenders are responsible for a
disproportionate amount of crime (the 50–10 or 80–20 rule), and this group can be responsible for
many crimes in a short time period (Martinez et al., 2017). Research results have shown highly skewed
offending rates, with some rates 10 to 50 times that of the average (Canela-Cacho, Blumstein, & Cohen,
1997; Marvell & Moody, 1998). Abel, Mittelman, and Becker (1985) found 70% of the paraphilic sex-
ual offenses they studied were committed by only 5% of the offenders. Skewed offending distributions
mean that although most criminals are not serial offenders, the majority of crime is serial. The current
method of detective case assignment often overlooks these connections.
Situation-based patterns are driven by the nature of the crime and/or by the conditions of the immedi-
ate environment. They can be effectively responded to by adopting a problem-oriented policing (POP)
approach to investigations (Eck, 1983), one concerned with examining the “where” as well as the
“who.” Mostly this has not occurred, but there are a few examples (see, for instance, Madensen, Herold,
Hammer, & Christenson, 2017).
Efforts to reduce a cluster of murders in Vancouver, British Columbia, provide an example of the
potential of this approach. There was a hot spot of murder in the Skid Road area; approximately one
sixth of the city’s homicides occurred within a two-block radius of a particular intersection (Coburn,
1988). Most of these murders happened during the early hours of the morning. Offender and victim
were typically both highly intoxicated. The most common weapon was a knife.
Police have traditionally responded to these murders by investigating them individually and, when
possible, arresting the killer. The situational characteristics of this particular crime cluster, however,
indicated the possibility of a preventive approach. Most of these murders were not planned but were
the outcomes of arguments that emerged during bootlegging parties (small groups of people drinking
bootleg liquor in hotel rooms or rooming houses after the local bars closed).
The response strategy included the following actions:
• The provincial government amended the liquor act to prohibit carrying a knife in a licensed premise.
• Police investigated bootleggers, charged them, and shut down their operations.
• Aggressive drunks arrested during the evening were held in jail until the bars closed, making it
difficult for them to then find a bootlegging party.
• Patrol officers responded to disturbances at such parties by breaking them up and sending everyone
Like an iceberg, these murders involved dynamics beneath their surface. Disrupting the situational
events that led up to the crimes helped stop them from occurring, which was contrary to the received
wisdom at the time that murder was not preventable. The combination of police investigation and crime
analysis, with a focus on both offenders and places, provided a more powerful approach for managing
the problem and reducing the likelihood of future such murders.
In another example, a detective in Edmonton, Alberta, noted that gas stations from one chain
reported numerous robberies. After conducting further investigation, he found that the robbers stole
only cigarettes (the high tax on cigarettes made them extremely valuable) and each station was served
by a single attendant in a small booth stocked with cigarettes, candy, and other items. The detective
14 ECK AND ROSSMO
Opportunies for crime
create paerns of crime
Some events, that form
the paerns, are
reported to the police.
Police invesgate these events, …
… and solve some of them.
Solved or not, detecves learn a great deal about
how crimes are conducted: the parcular methods
oﬀenders use, the sequence of acons they take,
the targets they select, the places they prefer, etc.
This informaon is crucial to problem
solving for prevenon as it helps address
solving prevents crimes.
Some events, that form
the paerns, are not
reported to the police.
FIGURE 3 Connecting crime solving and crime prevention
strongly encouraged the company that owned the chain to change the way the cigarettes were displayed
and sold so that they would be less vulnerable to robbery. The result was a substantial decline in these
crimes (Eck, 1997).
Thinkers and problem-solvers have more potential for crime control than do techno-bureaucrats
(especially those struggling to handle high production pressures). Perhaps we can learn something
from the Bow Street Runners set up by magistrate Henry Fielding in 1749 (Styles, 1983). The Runners
did not have a large bureaucratic structure and could not count on extensive technological assistance.
They therefore had to talk to people, spend time on the street, and be highly creative.
How does a police agency involve its detectives in problem solving as a systematic routine of every-
day operations, rather than as a side-business, only to be used because a particular detective has an
interest or because there is a crisis that needs resolving? We turn to that next.
5.4 Connect detectives to crime reduction
We begin with the basic fact that opportunities for crime create crime patterns. This is at the heart of
environmental criminology and has been well documented in hundreds of studies of many different
crime types across the globe (Wortley & Townsley, 2017). Progress in crime prevention is mainly
based on recognizing crime opportunities and on finding ways to alter them. This is also the principle
strategy employed within a problem-oriented approach to policing (Goldstein, 1990). And this is why
we have placed patterns of crime at the top of Figure 3. Victims and witnesses report many of the crime
events created by these crime opportunities to the police, but many other crimes do not get reported.
It is likely that the offenders involved in reported crimes committed some of the unreported crimes,
although it is usually difficult to know for certain. Continuing clockwise in Figure 3, the reported
crimes get some form of investigation even if it is only an initial enquiry by responding uniformed
officers. Patrol officers and detectives solve some of these investigated crimes, although as we have
seen, the chances of this vary by crime type and are typically low. This is where most of the efforts to
improve investigations stop.
Investigations, successful or unsuccessful, add to an investigator’s store of knowledge. This may
be particularly true for detectives who address numerous crimes over many years. Some of the
ECK AND ROSSMO 15
information they acquire is of limited use for solving individual crimes, so when police agencies
focus on clearance rates, this type of experience remains untapped. We suggest this knowledge has
great value to police and should be used. Detectives know much about various criminal methods.
During their work, they accumulate information on the processes offenders follow—crime scripts
(Cornish, 1994). They know what makes some targets more attractive to offenders than others. And
they often have some understanding of why some places have far more crime than others. They
may have learned a great deal about the behavior of victims as well, for example, what they were
typically doing just before the crime. If this information can be put to use in problem-solving efforts
(left side of Figure 3), detective expertise can help prevent crimes. The changes to the opportunity
structure from problem solving also alter the patterns of crimes reported to the police, completing the
Detective experience, consequently, can inform problem solving. Detectives might not lead these
efforts (although they could), but they are a potentially vital source of expertise for police problem
solvers (Goldstein, 1990). Problem solving can make a substantial contribution to crime prevention
(Weisburd, Telep, Hinkle, & Eck, 2010) by changing the underlying opportunity structure for offend-
ing, thereby altering the crime pattern. In short, the framework we have just described (and illustrated
in Figure 3) makes greater use of detectives by recognizing that they often know far more about crime
production than police agencies recognize. Here are four ways we can imagine their expertise being
used, even though there are undoubtedly numerous other approaches.
5.4.1 Routine debriefings of offenders and victims
As noted by Boba and Santos (2015), although detectives frequently interview offenders and victims,
the primary goal of these interviews is to determine who committed a crime and to gather evidence
for a successful prosecution. If police agencies relax their obsession with solution rates, and encourage
detectives to learn more about crime, their interviews could be even more helpful. We suggest that
much can be learned by using a second type of interview, one that is focused on learning how crimes
are committed rather than on simply solving them. There are two circumstances under which detectives
could conduct such interviews. First, after the investigation of a case is solved and adjudicated, detec-
tives could re-interview offenders and victims. Questions, particularly to offenders, can be phrased to
elicit their expertise while avoiding actual confessions. Second, similar interviews could be conducted
with former offenders. As in the first type, they would be treated as if they are “crime experts” the
detective wants to learn from. Many offenders may not wish to participate, but a surprising number
will welcome the chance to discuss their “work.” The results of both types of interviews would add
to the detective’s knowledge. If the transcripts of the interviews were analyzed, a crime intelligence
analyst could produce summary reports that would inform police officers throughout the agency. And
omnibus collections of these reports from multiple agencies could serve as a valuable knowledge base
for detectives, crime prevention practitioners, and researchers.
As a few victims, offenders, and places are disproportionately involved in crimes, focusing detectives
on repeats could help solve more crimes and reduce the likelihood of their reoccurrence. Rather than
just assigning cases to detectives as incidents get reported, detectives could be assigned to victims or
places. Consequently, a repeated victim would be assigned to the same detective. A detective might
take responsibility for all crime emanating from a single location. And some detectives might specialize
in knowing everything possible about highly active offenders (to some degree, this is already done by
16 ECK AND ROSSMO
5.4.3 Place-based investigations
Tamara and Maris Herold proposed a particularly innovative approach to reducing crime. They
noted that crime places are often connected, and that some of the places important for crime are not
necessarily the actual sites of crime. The reason some high hot spots persist, even in the face of police
activity, is that the network of places is not addressed. They suggested these places be investigated
with the objective of making the micro-ecology of crime untenable to offenders (Madensen et al.,
2017). These ideas formed the basis for the Cincinnati Police’s PIVOT (Place-based Investigations of
Violent Offender Territories) program, which won the Herman Goldstein Award for Problem-Solving
Excellence in 2017 (Hammer, Christenson, & Madensen, 2017). Central to place-based investigations
is the use of detectives to determine how networks of places contribute to crime and, if necessary,
investigate the criminal involvement of place managers who facilitate crime (e.g., the convenience
store owner who services a local drug market or restocks his inventory by soliciting thieves to shoplift
from other businesses). Place-based investigations are cousins to victim-based investigations (for
example, to reduce domestic violence) or to serious offender investigations (as in focused deterrence
programs designed to reduce homicides among rival gangs). In all such investigations, the goal is to
reduce crime, not to simply rack up arrests (although arrests are one of several means for achieving
5.4.4 Detective involvement in problem solving
The notion that detectives can make valuable contributions to problem solving is not new; one of us
proposed this more than 30 years ago (Eck, 1983). Nevertheless, detective involvement in problem
solving is limited and intermittent rather than common and systematic. We are uncertain why this is
the case. Detectives can play several different roles in problem solving. They can be consultants to
problem-solving teams, like other experts from whom teams seek advice. They can be members of
problem-solving teams. And they can lead problem-solving efforts. In addition, police should consider
closer ties between specialized units dedicated to preventing crime and investigative units. Detectives
often have considerable insights into ways crimes can be prevented that problem-solving or crime
prevention units could put to use.
We began by showing the ability to solve crimes is limited. In fact, over many decades, the police in the
United States have become worse at fulfilling this traditional role. Their ability to solve crimes did not
improve when crime dropped precipitously in the 1990s, even though detective workloads should have
gone down. Perhaps crimes have become harder to solve. This might have occurred for two reasons.
First, offenders may have become better at learning from theirs and others’ experiences and leave
fewer clues behind today than they did 50 years ago (perhaps influenced by the so-called CSI effect).
To maintain their solution effectiveness, detectives would need to spend more effort on the average
crime than they did in the 1960s. Alternatively, the legal–administrative requirements on detectives
may have increased, including the requirement to collect more and better evidence. If so, detectives
must now expend greater effort processing information. We are not aware of any convincing evidence
for or against the smarter criminal suggestion, but there is evidence for the increasing requirements
hypothesis. In either case, police administrators would have had to increase investigative resources
to maintain the same success rate. But Horvath and colleagues (2003) found police agencies employ
almost the same proportion of detectives in 2003 as they did in the 1970s.11
ECK AND ROSSMO 17
So maybe police should invest more in detective work. This would require either increasing police
staffing (and budgets) or shifting officers from patrol to investigations. The patrol force has contributed
the most, however, to police effectiveness over the last 50 years. Perhaps the answer is renewing the
1970s program of managing criminal investigations to improve their efficiency. We are skeptical of
this response. It seems unlikely that having detectives operate as they have always done, with only
marginal improvements in organization, management, or procedures, will make much difference.
Traditionally, the detective function is an essential, significant, and expensive part of the policing
enterprise. Currently, on average, about one out of every six police officers works in a criminal inves-
tigative capacity (Greenwood & Petersilia, 1975; Horvath et al., 2003). Braga et al. (2011, p. 4) argued,
“it is time for a period of innovation in the work of criminal investigators that develops their potential
for controlling crime rather than handling only the cases that come their way.” They cautioned that this
does not change the main purpose of detectives: holding offenders accountable for their crimes and
providing a measure of closure to victims and their families.
Since at least 1990, efforts to improve policing have changed the main purpose of patrol operations.
Handling calls for service was a principle function of patrol, as was roaming about between calls.
Efforts to improve police ability to reduce crime have downplayed call handling and roaming and have
promoted proactive attention to crime hot spots and other patterns. Police still roam about. And they
still handle calls. These functions, however, have become increasingly circumscribed as it became
clear they rarely made the public safer. It is time police leaders consider making analogous changes to
What, why, and how police investigators do their work should be rethought and reoriented to a larger
crime control and prevention mandate. Previous researchers have proposed model investigative proce-
dures, additional resources, improved relationships, and better training. Most of these proposals have
been designed to help police gather more evidence. But detectives also need to evaluate and analyze
carefully the evidence collected during an investigation and to understand correctly its significance
and reliability. Finally, there is a need to improve detective thinking, in particular, to recognize and
mitigate the problems of cognitive biases and thinking errors.
Any effort to rethink and retask the criminal investigation function is unlikely to be effective unless
detective units are properly resourced in terms of personnel, initial and ongoing training, mentor-
ship and supervision, support personnel, and forensic and information technology. Without adequate
resources, investigative efforts and objectives will be vulnerable to distortion from extraneous influ-
ences. Establishing the value of this investment is an important policy question. We know violent crime
is expensive; the combined victim, justice system, and social costs of a single murder are in the millions
of dollars (Mayhew, 2003; McCollister, French, & Fang, 2010; Miller, Cohen, & Wiersema, 1996).
Unfortunately, we know extremely little about the relationship between investigative resources and
investigative results. The limited and weak evidence available casts doubt on the emphasis on tech-
nology; if technology made a dramatic impact on crime solutions, Figures 1 and 2 would look much
different. We know even less about detective staffing levels and outcomes, although we would have
expected crime clearances to begin improving as crime dropped in the 1990s. We know little about the
effects of detectives’ relationships with community members, despite old research findings that decen-
tralization improves clearance rates (Bloch & Bell, 1976). Although we assume that solving crimes is
an important police service, there is no evidence showing that public satisfaction with police, percep-
tions of police legitimacy, or fear of crime is influenced positively or negatively by current investigative
Police agencies need to go beyond thinking of detective work as being the production of solutions
to crime. They need to go beyond improving the management of investigations (which have typically
been more for the benefit of managers, rather than of detectives). Police agencies need to address
18 ECK AND ROSSMO
the quality and the quantity of solutions that can further justice. But even this is unlikely to make a
measurable impact on public safety unless detectives are better integrated into the prevention function
of policing. Detectives have much they can contribute to the prevention of crime, but for the most part,
police agencies have not called on them systematically and routinely to do so. We have outlined several
means for increasing and strengthening their contributions. Undoubtedly police can discover more
possibilities if they set their minds to it. Similarly, police researchers have been negligent in examining
how detectives can contribute to crime reduction; they too have failed to challenge the assumption that
investigations are mostly about solving crimes and making arrests. The overall improvements in police
effectiveness since around 1990 are in large part a result of police–researcher collaborations (Sherman,
2013). If investigations are to be improved, these two partners need to work in concert.
The amount of scholarly literature on the criminal investigative function is surprisingly limited. This
gap in the research was mentioned in the RAND study in the 1970s and again in Horvath et al.’s follow-
up survey in the early 2000s. An analysis of presentation topics after the 2002 Academy of Criminal
Justice Sciences meeting determined that only 2% of the papers were on police investigations. Although
the other components of the police function have been extensively studied, for some reason, the criminal
investigative process continues to be ignored. The existing research has primarily been focused on
technical issues, such as cybercrime or DNA, or (more recently) on wrongful convictions. If policing
is to become fully evidence based, scholars have to increase the quantity and quality of investigations
research dramatically. Considerable research is needed on the impact of alternative ways of organizing
investigations on case outcomes, the utility of focusing on repeats (offenders, victims, and places),
methods for encouraging the public to report crime case information to police, and understanding
how physical evidence can best impact case resolution. Attention from the academic community to
the importance of the role played by detectives in controlling crime, maintaining social order, and
promoting police legitimacy is overdue.
Nevertheless, we are aware of journalist Eric Sevareid’s caution, “The chief cause of problems is
solutions.” Re-envisioning the criminal investigation function along the lines we have described is
likely to be a matter of two steps forward and one back. Many seemingly good ideas will turn out to
be less helpful than their proponents (including us) thought, but a few might be. Consequently, cre-
ativity, experimentation, and evaluation are needed, along with dedication, persistence, and humility.
The detective function has great potential for reducing crime, but to date, it has suffered from neglect,
conservative traditions, and organizational dogma. It is time for that to change.
1We will call plainclothes police who specialize in investigations detectives despite the fact that such specialists go by
a wide variety of titles and that many people in police agencies contribute to investigations—patrol officers, evidence
technicians, crime analysts, and others. We do this merely for ease of writing.
2One reason for this might be shoplifting, which comprises a substantial portion of larceny-theft reports and clearances.
Usually, the report of a shoplifting event is coupled with a suspect detained by the business. So variations in shoplifting
reports to police might drive these figures. We are only speculating, and research is necessary to determine whether
our guess is correct.
3Not knowing who solves crimes presents a problem. Although our focus here is on the detective function, clearance
probabilities are a complex product of crime type, community support, patrol work, investigative operations, agency
resources, and legal policies—any or all of which could have influenced the time-series charts in Figures 1 and 2. Let
us imagine that community support hypothetically accounted for 75% of robbery clearances in 1960. But then, for var-
ious reasons, this contribution declined over the next 58 years. At the same time, for other reasons (e.g., improvements
in forensics and technology), detective-related clearances improved. Because of its larger base rate, the deteriora-
tion in community support would hide any increases resulting from better investigations. Although we do not know
ECK AND ROSSMO 19
whether something like this actually happened, we lack the evidence to eliminate it from consideration. Perhaps other
researchers would be interested in exploring this.
4The significant increase in the public’s access to newspapers in eighteenth-century England was important to criminal
investigations because of the information published on wanted suspects, stolen property, and reward offers (Styles,
5A simple thought experiment helps frame the deterrence debate. Could we expect implications for offender deterrence
if detectives stopped arresting criminals? If so, do we have any reason to believe we are currently at the optimal arrest-
6This is a compounding problem, much like interest earning on a bank account. For example, assume a youth familiar
with the data in Figure 2 believes he has a 10% chance of being arrested for any particular burglary. This prospective
burglar might view these as good odds, particularly as he is young and foolish. If he is older and smarter, and considers
a series of 25 burglaries, he may realize he has a ∼93% chance of being caught sometime during his crime spree. If he
improves his skills, he can lower his probability of being detected. But if the police accumulate intelligence about him,
his survival chances become bleaker. In either case, his “career” risk is substantially higher than an estimate based on
a conservative interpretation of the burglary clearance data. If burglars are not smart, and only consider their chances
for success one burglary at a time, the deterrent threat of a low clearance rate is not great. The willingness to accept a
gamble depending on the number of trials is known in economics as Samuelson’s Problem (Kahneman, 2011).
7Wrongful convictions, an overt problem with identifiable solutions, have prompted much more attention and demands
for reform from academics, politicians, and the media than have unsolved crimes (Batts, deLone, & Stephens, 2014).
8Bayesian probability theory provides the necessary analytic framework (Blair & Rossmo, 2010; Robertson & Vignaux,
9Evidence is a recorded fact relevant to the crime, the origin of which can be identified (e.g., witness statement, crime
scene photograph, laboratory report, etc.). Theories, assumptions, and beliefs are not evidence.
10 Imprecise statements of probability underlie many critical concepts in criminal law: probable grounds, beyond a rea-
sonable doubt, reasonable degree of scientific certainty, common, risky, and so on.
11 This comparison should be interpreted with some caution. Although the research teams in the two studies found similar
national averages, important changes at the individual agency level may have occurred. Also, Horvath’s team collected
their data almost 20 years ago, so it is possible the allocation of police resources and functions has changed since
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John E. Eck is a professor of criminal justice at the University of Cincinnati. He received his
Ph.D. in criminology from the University of Maryland—College Park in 1994. From 1977 to 1995,
Prof. Eck directed research for the Police Executive Research Forum—a police chief membership
and research organization—where he studied criminal investigation management, problem-oriented
policing, and drug control strategies. He has written numerous papers, books, and monographs for
police practitioners and for academic researchers. Prof. Eck is the recipient of the 2016 Ronald
V. Clarke ECCA Award for Fundamental Contributions to Environmental Criminology and Crime
D. Kim Rossmo holds the University Chair in Criminology and is the director of the Center for
Geospatial Intelligence and Investigation in the School of Criminal Justice at Texas State Univer-
sity. He has researched and published in the areas of environmental criminology, the geography
of crime, and criminal investigations. Prof. Rossmo is a member of the Police Investigative Oper-
ations Committee of the IACP and was formerly a detective inspector with the Vancouver Police
Department. He received his Ph.D. in criminology from Simon Fraser University.
How to cite this article: Eck JE, Rossmo DK. The new detective: Rethinking criminal investi-
gations. Criminol Public Policy. 2019;1–22. https://doi.org/10.1111/1745-9133.12450