Файл: [D._Kim_Rossmo]_Geographic_Profiling(BookFi.org).pdf

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The nature of criminal predators causes unique problems for law enforce-
ment, requiring special police responses and investigative strategies. It has
been suggested there are only three ways to solve a crime: (1) confession;
(2) witness; or (3) physical evidence (Klockars & Mastrofski, 1991; Simon,
1991). Traditionally, the search for witnesses, suspects, and evidence has
followed a path outwards from the victim and crime scene. Most homicides
are cleared for the simple reason that they involve people who know each
other, and the process of offender identification may only require suspect
elimination. Boyd (1988) found that 80% of convicted murderers in Canada
had killed either family members or acquaintances, while Silverman and
Kennedy (1993) determined that 8% of Canadian murders from 1961 to
1990 involved strangers, and 14% occurred during the commission of
another crime. Such obvious connections rarely exist in cases of serial mur-
der, rape, or arson. The lack of relationship between victim and offender
makes these crimes difficult to solve (Skogan & Antunes, 1979). Working
outwards from the victim during the investigation of a stranger attack is a
difficult task. The alternative, then, is to work inwards, trying to establish
some type of link between potential suspects and the victim or crime scene.

This process requires the determination and delineation of a likely group

of potential suspects, a process referred to by Kind (1987b) as “framing,” and
by Skogan and Antunes (1979) as establishing the “circle of investigation.”
This effort typically involves the inspection of individuals with relevant crim-
inal or psychiatric records, the accumulation of intelligence, and the collec-
tion of suspect tips from members of the public. The Rand study of the
criminal investigation process found the information that led to solved crimes
most likely came from the public, then from patrol officers, and third, from
detectives (Chaiken, Greenwood, & Petersilia, 1991). This underlines the
importance of effective channels of communication between the police and
the community, and within the police organization.

Canadian and British police officials believe the performance of their

information management systems have much to do with their ability to utilize
large amounts of data collected during major inquiries (Green & Whitmore,
1993). In 1990, a typical year, the U.K. had a 90% homicide clearance rate,
Canada, 78%, but the U.S., only 67%. The application of information theory
concepts to the policing process has significant potential (see Krippendorff,
1986). But while information is an important determinant of the likelihood
that police will solve a crime, it must be of a useful nature (Kind, 1987b;
Lyman, 1993; Skogan & Antunes, 1979). The determination of what is help-
ful, and what is not, is a less than straightforward task.

The investigative process is based upon the proper collection, analysis,

and sharing of information. But not all information has the same value, and
investigators must be wary of “static” or “noise” — useless or misleading

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information. And because investigative efforts can produce hundreds and
even thousands of potential suspects, problems with information overload
often develop. This is the classic needle in the haystack problem (see the
discussion on the Gainesville Slayings investigation in Fox & Levin, 1994).

In the still unsolved Green River Killer case, for example, 18,000 suspect

names have been collected, but as of February 1992, the police have only had
time and resources to investigate fewer than 12,000 of these (Montgomery,
1993). Police have gathered 8000 tangible items of evidence from the crime
scenes, and a single television special on the case generated 3500 tips. In Britain,
the nationwide search for Robert Black, the Staffordshire serial murderer,
amassed details on 185,000 people and tens of thousands of vehicles over the
course of 11 years before the child killer was finally caught (Wyre & Tate, 1995).

The Narborough Murder Enquiry, a massive four-year manhunt in

Leicestershire, England, obtained close to 4000 blood samples for DNA test-
ing prior to charging Colin Pitchfork with the deaths of two teenage girls
(Wambaugh, 1989). The Yorkshire Ripper case amassed 268,000 names
before it was over; police initiated 115,000 actions, visited 27,000 houses, and
took 31,000 statements. Up to 1000 letters were received daily from the public,
and a total of 5.4 million vehicle registration numbers were recorded by
investigators (Doney, 1990; Nicholson, 1979).

A corollary to the problem of information overload is the high cost

associated with any extensive, long-term investigation. The final price of the
Atlanta Child Murders investigation was more than $9 million (Dettlinger &
Prugh, 1983), while the Yorkshire Ripper Inquiry involved a total of 5 million
hours of police time (Doney, 1990). By early 1992, the still unsuccessful Green
River Task Force had accumulated expenses of approximately $20 million
(Montgomery, 1993).

It is important for police detectives to know which offences are con-

nected, and which ones are not, so information between related cases can be
collated and compared. Confusion over which crimes are part of the series
has developed in several investigations involving serial killers, including
Henry Lee Lucas, Peter Sutcliffe, and Clifford Olson. In other cases, partic-
ularly those involving high risk victims, authorities may not be aware a
predator is operating within their jurisdiction.

The problem of series identification becomes much worse with mobile

offenders who commit crimes in different areas. When a criminal investiga-
tion has to cross jurisdictional boundaries, issues of coordination, coopera-
tion, and competition arise. This “lack of sharing or coordination of
investigative information relating to unsolved murders and to the lack of
adequate networking among law enforcement agencies” has been termed
linkage blindness (Egger, 1984). The problem can also occur within a single
large police organization, as happened in New York City when the Son of

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Sam killed his early victims in different precincts (Ressler & Shachtman,
1992). Serial rape is just as susceptible to linkage blindness, but serial arson
is less so due to the limited geographic range of the typical arsonist.

Several other investigative difficulties exist that complicate efforts to link

crimes and apprehend serial killers and violent sex offenders (Egger, 1990,
1998; Holmes & De Burger, 1988; James, 1991; O’Reilly-Fleming, 1992).
These problems include:

•

The intense public fear, media interest, and political pressure sur-
rounding these cases;

•

Police inexperience

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 with serial murder cases, including an unwill-

ingness to acknowledge the situation and commit sufficient resources,
ignorance of appropriate investigative strategies, and overlooking vic-
timological information;

•

The complexity of personnel and coordination logistics, especially
when multiple jurisdictions and agencies are involved. In the Yorkshire
Ripper case, for example, 250 full-time detectives were assigned for
over a three-year period (Doney, 1990);

•

Offender learning and improvement from “practice;”

•

Copy cat crimes; and

•

False confessions from unbalanced people attracted by the notorious
publicity.

In a comparison of solved (n = 399) and unsolved (n = 75) serial murder

cases, Mott (1999) correctly hypothesized the former group would be char-
acterized by higher killing rates, lower victim vulnerability, and indoor body
disposals. Contrary to her expectations, however, offender mobility and mul-
tiple crime sites were also related positively to crime solution, though she
cautions these results may be data artifacts. Discriminant analysis correctly
classified 75.2% of the cases.

4.2 Police Strategies

For heaven’s sake catch me Before I kill more. I cannot control myself.

—Message written in lipstick on the living room wall of Frances Brown,

victim of serial murderer William Heirens; Kennedy, 1991, p. 38

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Many countries, including Britain, Canada, and the U.S., are now attempting to pool

investigative expertise in “low volume crimes.” Perhaps the current record is held by
Captain Piet Byleveld of the South African Police Service in Johannesburg, who has inves-
tigated six serial murder cases during his career.

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In an attempt to overcome the obstacles facing serial violent crime cases, a
variety of law enforcement strategies have been developed over the past few
years (Egger, 1990). One of the cornerstones of this effort has been the creation
and use of behavioural science-based methods in the police investigative pro-
cess. The application of scientific studies of human behaviour to analyze crim-
inal actions has led to linkage analysis systems, criminal profiling, geographic
profiling, and crime-specific statistical databases. This field is sometimes
referred to as forensic behavioural science to distinguish it from the more
academic pursuits of traditional psychology and sociology (though one could
argue that “forensic,” which means “belonging to courts of law,” is not the most
appropriate term for a set of methods primarily investigative in nature).

Connected to the behavioural science approach has been the design of

information management systems and suspect prioritization methods to
enhance investigative effectiveness and efficiency (Jackson, van den Eshof, &
de Kleuver, 1994; Ressler & Shachtman, 1992). Scrutiny of people of interest,
in the effort to work backwards from them to the victim, is a difficult and
time consuming process. Thorough interrogations of suspects, detailed inter-
views of their associates (who may be witnesses, whether they know it or
not), and extensive searches for, and analyses of, physical evidence consume
valuable and limited resources. By using a methodology to prioritize the
police approach, investigative efforts can be tailored to the priority rating of
the individual suspect. By focusing on the most probable suspects, all else
being equal, the offender will more likely be identified sooner.

Kind (1987b, 1990) suggests the use of “frames” and “forms” to help

prioritize suspects during the course of a police investigation. Frames are
flexible and fuzzy enclosures employed to delineate potential suspects, while
forms are tendencies for groups of people to behave in like fashion. Utilized
in conjunction with each other, these concepts produce combined (i.e., inter-
secting) frames that outline the most productive lines of inquiry. While all
criminal investigations can employ this form of information management,
the approach is particularly useful in large-scale major inquiries.

4.2.1 Linkage Analysis

When FBI Special Agent Clarice Starling finds a Black Witch Moth (

Erebus

odora

) chrysalis lodged in the throat of serial killer Buffalo Bill’s latest victim,

a connection is soon made to another murder. But real crimes, unlike those
in Thomas Harris’ popular novel 

Silence of the Lambs

 (1988), are often much

more difficult to link. “Prostitute strangled, dumped at the side of the road,
no physical evidence,” is a depressingly familiar crime scene description.

Establishing which offences are part of a series is an important and

essential task in the investigation of serial crime (see Gottlieb, Arenberg, &
Singh, 1998). This process is known as linkage analysis

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 or comparative case

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analysis (CCA). Realizing the extent of the crime pattern helps determine
the appropriate level of police response, facilitates information sharing
between investigators and jurisdictions, outlines case similarities, and iden-
tifies common suspects. If and when the case is solved, additional crimes are
cleared and the court delivers a more appropriate sentence (including dan-
gerous offender or habitual felon designations). Knowing all the pieces of
the puzzle allows a more comprehensive picture of the offender to be formed
and prevents linkage blindness from occurring.

For example, during 1993 and 1994 the Tag Team Rapists broke into

several ground floor suites in Surrey, British Columbia, and attacked single
women, many of whom had children. The crimes were occurring close
together, but within two separate neighbourhoods (Newton and Bear Creek)
that were a significant distance apart. One of the questions concerning inves-
tigators was the offender’s method of travel — on foot or by vehicle? Project
Escalate’s first step was to examine all possible related crimes, including sexual
assaults, attempts, burglaries, and prowlings. Eventually 14 different incidents
were identified as being part of the series. Weather conditions on the dates
and times of these events were then checked with the Environment Canada
Vancouver Weather Information office. It was determined that every one of
these incidents occurred on a dry night. The probability of this many fall
and winter nights in the rainy Pacific Northwest without precipitation is very
low. This suggested that the offenders intentionally refrained from hunting
during inclement weather, an indicator they usually walked. The two offend-
ers have now been apprehended and convicted, and this prediction turned
out to be accurate. But the question of offender transportation could not be
answered with any degree of confidence until after the linkage analysis had
been completed and as many of the pieces of the puzzle as possible assembled.

There are three main methods used by police investigators to link

crimes prior to an offender’s apprehension. They are: (1) physical evidence;
(2) offender description; and (3) crime scene behaviour. Each method has
its strengths and weaknesses. It is not uncommon for a series of crimes to
be connected through a combination of these means.

4.2.1.1

Physical Evidence

Physical evidence provides the most certain means of linking crimes, though
evidence of a type suitable for doing so may not be present in every case.
One of the more powerful forensic methods, DNA profiling, has been her-
alded as the most revolutionary technology in the field of criminal

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This is not to be confused with the similar but distinct function of “link analysis,”

performed on such systems as the i2 

Analyst’s Notebook

. Link analysis examines inter-

and intra-crime associations between names, telephone numbers, vehicles and the like.
Linkage analysis considers likelihood of crime similarity.