Using Dna To Solve Cold Case
U.S. Department of Justice
Office of Justice Programs
JUL
National Institute of Justice
Y
0
2
Special
REPORT
Using DNA to Solve Cold Cases
U.S. Department of Justice
Office of Justice Programs
810 Seventh Street N.W.
Washington, DC 20531
John Ashcroft
Attorney General
Deborah J. Daniels
Assistant Attorney General
Sarah V. Hart
Director, National Institute of Justice
This and other publications and products of
the U.S. Department of Justice, Office of
Justice Programs and NIJ can be found on
the World Wide Web at the following sites:
Office of Justice Programs
http://www.ojp.usdoj.gov
National Institute of Justice
http://www.ojp.usdoj.gov/nij
Photographs copyright © 2002 PhotoDisc, Inc.
JULY 02
Using DNA to Solve Cold Cases
NCJ 194197
Sarah V. Hart
Director
National Institute of Justice
This document is not intended to create, does not create, and may not be relied upon to
create any rights, substantive or procedural, enforceable at law by any party in any matter
civil or criminal.
Findings and conclusions of the research reported here are those of the authors and do not
reflect the official position or policies of the U.S. Department of Justice.
The National Institute of Justice is a component of the Office of Justice Programs, which also
includes the Bureau of Justice Assistance, the Bureau of Justice Statistics, the Office of Juvenile
Justice and Delinquency Prevention, and the Office for Victims of Crime.
National Commission on the
Future of DNA Evidence
In 1995, the National Institute of Justice
collection, laboratory funding, legal issues,
(NIJ) began research that would attempt
and research and development. The
to identify how often DNA had exonerated
Commission’s working groups, consisting
wrongfully convicted defendants. After
of commissioners and other experts,
extensive study, NIJ published the report
researched and examined various topics
Convicted by Juries, Exonerated by
and reported back to the Commission. The
Science: Case Studies in the Use of DNA
working groups’ reports were submitted
Evidence to Establish Innocence After
to the full Commission for approval,
Trial, which presents case studies of 28
amendment, or further discussion and pro-
inmates for whom DNA analysis was
vided the Commission with background
exculpatory.
for its recommendations to the Attorney
General.
On learning of the breadth and scope of
the issues related to forensic DNA, the
By nature of its representative composition
Attorney General asked NIJ to establish
and its use of numerous working groups,
the National Commission on the Future of
the Commission received valuable input
DNA Evidence as a means to examine the
from all areas of the criminal justice sys-
most effective use of DNA in the criminal
tem. The broad scope of that input enabled
justice system. The Commission was
the Commission to develop recommenda-
appointed by the NIJ Director and repre-
tions that both maximize the investigative
sented the broad spectrum of the criminal
value of the technology and address the
justice system. Chaired by the Honorable
issues raised by its application.
Shirley S. Abrahamson, Chief Justice of
the Wisconsin Supreme Court, the Com-
mission consisted of representatives from
Commission members
the prosecution, the defense bar, law
enforcement, the scientific community,
Chair
the medical examiner community, acade-
mia, and victims’ rights organizations.
The Honorable Shirley S. Abrahamson
Chief Justice
The Commission’s charge was to submit
Wisconsin Supreme Court
recommendations to the Attorney General
that will help ensure the best use of DNA
Members
as a crimefighting tool and foster its use
throughout the entire criminal justice
Dwight E. Adams
system. Other focal areas for the Com-
Director
mission’s consideration included crime
Federal Bureau of Investigation Laboratory
scene investigation and evidence
iii
SPECIAL REPORT / JULY 02
Jan S. Bashinski
Ronald S. Reinstein
Chief
Associate Presiding Judge
Bureau of Forensic Services
Superior Court of Arizona
California Department of Justice
Maricopa County, Arizona
Sacramento, California
Darrell L. Sanders
George W. Clarke
Chief
Deputy District Attorney
Frankfort Police Department
San Diego, California
Frankfort, Illinois
James F. Crow
Barry C. Scheck
Professor
Professor
Department of Genetics
Cardozo Law School
University of Wisconsin
New York, New York
Lloyd N. Cutler
Michael Smith
Wilmer, Cutler & Pickering
Professor
Washington, D.C.
University of Wisconsin Law School
Joseph H. Davis
Jeffrey E. Thoma
Former Director
Public Defender
Miami-Dade Medical Examiner
Mendocino County, California
Department
Kathryn M. Turman
Paul B. Ferrara
Director
Director
Office for Victim Assistance
Division of Forensic Sciences
Federal Bureau of Investigation
Commonwealth of Virginia
William Webster
Norman Gahn
Milbank, Tweed, Hadley & McCloy
Assistant District Attorney
Washington, D.C.
Milwaukee County, Wisconsin
James R. Wooley
Terrance W. Gainer
Baker & Hostetler
Executive Assistant Chief
Cleveland, Ohio
Metropolitan Police Department
Washington, D.C.
Commission staff
Terry G. Hillard
Christopher H. Asplen
Superintendent of Police
Executive Director
Chicago Police Department
Chicago, Illinois
Lisa Forman
Deputy Director
Aaron D. Kennard
Sheriff
Robin W. Jones
Salt Lake County, Utah
Executive Assistant
Philip Reilly
Interleukin Genetics
Waltham, Massachusetts
iv
USING DNA TO SOLVE COLD CASES
Crime Scene Investigation
Working Group
The Crime Scene Investigation Working
review with a specific emphasis on using
Group is a multidisciplinary group of criminal
DNA evidence to solve previously unsolv-
justice professionals from across the United
able crimes. Although DNA is not the
States who represent both urban and rural
only forensic tool that can be valuable to
jurisdictions. Working group members and
unsolved case investigations, advance-
contributors were recommended and
ments in DNA technology and the success
selected for their experience in the area of
of DNA database systems have inspired
criminal investigation and evidence collec-
law enforcement agencies throughout the
tion from the standpoints of law enforce-
country to reevaluate cold cases for DNA
ment, prosecution, defense, the forensic
evidence. As law enforcement profession-
laboratory, and victim assistance.
als progress through investigations, how-
ever, they should keep in mind the array of
DNA has proven to be a powerful tool in
other technology advancements, such as
the fight against crime. DNA evidence can
improved ballistics and fingerprint data-
identify suspects, convict the guilty, and
bases, which may substantially advance
exonerate the innocent. Throughout the
a case beyond its original level.
Nation, criminal justice professionals are
discovering that advancements in DNA
Chair
technology are breathing new life into old,
cold, or unsolved criminal cases. Evidence
Terrance W. Gainer
that was previously unsuitable for DNA
Executive Assistant Chief
testing because a biological sample was
Metropolitan Police Department
too small or degraded may now yield a
Washington, D.C.
DNA profile. Development of the Com-
bined DNA Index System (CODIS) at the
Members
State and national levels enables law
enforcement to aid investigations by effec-
Susan Ballou
tively and efficiently identifying suspects
Office of Law Enforcement Standards
and linking serial crimes to each other. The
National Institute of Standards and
National Commission on the Future of
Technology
DNA Evidence made clear, however, that
Gaithersburg, Maryland
we must dedicate more resources to
empower law enforcement to use this
Jan S. Bashinski
technology quickly and effectively.
Chief
Bureau of Forensic Services
Using DNA to Solve Cold Cases is intend-
California Department of Justice
ed for use by law enforcement and other
Sacramento, California
criminal justice professionals who have
the responsibility for reviewing and inves-
Sue Brown
tigating unsolved cases. This report will
INOVA Fairfax Hospital
provide basic information to assist agen-
SANE Program
cies in the complex process of case
Falls Church, Virginia
v
SPECIAL REPORT / JULY 02
Lee Colwell
Darrell L. Sanders
Director
Chief
Criminal Justice Institute
Frankfort Police Department
University of Arkansas System
Frankfort, Illinois
Little Rock, Arkansas
Clay Strange
Thomas J. Cronin
Assistant District Attorney
Chief
Travis County District Attorney’s Office
City of Coeur d’Alene Police Department
Austin, Texas
Coeur d’Alene, Idaho
Contributors
Terry G. Hillard
Superintendent of Police
Cheryl May
Chicago Police Department
Assistant Director
Chicago, Illinois
Forensic Sciences Education Center
Little Rock, Arkansas
Mark Johnsey
Master Sergeant (Ret.)
William McIntyre
Division of Forensic Services
Detective Sergeant (Ret.)
Illinois State Police Department
Atlantic County Prosecutor’s Office
Springfield, Illinois
Homicide Unit
Hammonton, New Jersey
Christopher Plourd
Attorney at Law
San Diego, California
vi
Contents
National Commission on the Future of DNA Evidence . . . . . . . . . . . . . . . . . . . . . iii
Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
The Long and Short of DNA. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5
How Can DNA Databases Aid Investigations? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Practical Considerations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Identifying, Analyzing, and Prioritizing Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
vii
Introduction
In 1990, a series of brutal attacks on elder-
had been convicted of shooting into an
ly victims occurred in Goldsboro, North
occupied dwelling, an offense that
Carolina, by an unknown individual dubbed
requires inclusion in the North Carolina
the “Night Stalker.” During one such
DNA database. The suspect was brought
attack in March, an elderly woman was
into custody for questioning and was
brutally raped and almost murdered. Her
served with a search warrant to obtain a
daughter’s early arrival home was the only
sample of his blood. That sample was ana-
thing that saved the woman’s life. The
lyzed and compared to the crime scene
suspect fled, leaving behind materials
evidence, thereby confirming the DNA
intended to burn the residence and the
database match. When confronted with
victim in an attempt to conceal the crime.
the DNA evidence, the suspect confessed
In July 1990, another elderly woman was
to all three crimes.
brutally raped and murdered in her home.
Three months later, a third elderly woman
Mark Nelson, special agent in charge of
was raped and stabbed to death. Her hus-
the North Carolina State Crime Laboratory,
band was also murdered. Their house
said, “Even though these terrible crimes
was burned in an attempt to cover up the
occurred more than 10 years ago, we
crime, but fire/rescue personnel pulled
never gave up hope of solving them one
the bodies from the house before it was
day.”
engulfed in flames.
Every law enforcement department
When DNA analysis was conducted on
throughout the country has unsolved
biological evidence collected from vaginal
cases that could be solved through recent
swabs from each victim, authorities con-
advancements in DNA technology. Today,
cluded that the same perpetrator had
investigators who understand which evi-
committed all three crimes. However,
dence may yield a DNA profile can identify
there was no suspect.
a suspect in ways previously seen only on
television. Evidence invisible to the naked
For 10 years, both the Goldsboro Police
eye can be the key to solving a residential
Department and the crime laboratory
burglary, sexual assault, or murder. The
refused to forget about these cases. With
saliva on the stamp of a stalker’s threaten-
funding from the National Institute of
ing letter, the perspiration on a rapist’s
Justice, the crime laboratory retested the
mask, or the skin cells shed on the liga-
biological evidence in all three cases with
ture of a strangled child may hold the key
newer DNA technology and entered the
to solving a crime.
DNA profiles into North Carolina’s DNA
database. This would allow the DNA pro-
In Austin, Texas, for example, an investi-
file developed from the crime scene evi-
gator knowledgeable about DNA technolo-
dence to be compared to thousands of
gy was able to solve the rape of a local
convicted offender profiles already in the
college student. Having read about the
database.
potential for obtaining DNA evidence from
the ligature used to strangle a victim, the
In April 2001, a “cold hit” was made to
investigator requested DNA testing on the
the perpetrator’s convicted offender DNA
phone cord used to choke the victim in his
profile in the database. The perpetrator
case. He realized that in the course of
1
SPECIAL REPORT / JULY 02
choking someone, enough force and fric-
Although DNA is not the only forensic tool
tion is applied to the rope or cord that the
available for the investigation of unsolved
perpetrator’s skins cells may rub off his
cases, advancements in DNA testing and
hands and be left on the ligature.
the success of DNA database systems
have inspired law enforcement agencies
The investigator’s request paid off in an
throughout the country to reevaluate
unanticipated way. In spite of the attack-
cases previously thought unsolvable. The
er’s attempt to avoid identification through
purpose of this report is to provide law
DNA evidence by wearing both a condom
enforcement with a practical resource for
and rubber gloves, a reliable DNA profile
the review of old, cold, or unsolved cases
was developed from the evidence. During
that may be solved through DNA technolo-
the struggle, the attacker was forced to
gy and DNA databases. “The Long and
use one hand to hold the victim down,
Short of DNA” and “How Can DNA
leaving only one hand to pull the phone
Databases Aid Investigations?” will edu-
cord tight. The attacker had to grab the
cate the reader about the science and
remaining end of the cord with his mouth,
technology of DNA testing and DNA data-
thereby depositing his saliva on the cord.
bases. “Practical Considerations” provides
The successful
Although the developed profile came from
important background information on legal
review and
saliva rather than skin, DNA not only
and practical considerations regarding the
solved the case in Austin, but also linked
application of DNA technology to old, cold,
investigation of
the perpetrator to a similar sexual assault
or unsolved cases. Finally, a step-by-step
unsolved cases
in Waco.
process is provided to help investigators
select cases that would most likely be
require coopera-
Without the investigator’s understanding
solved with DNA evidence. As investiga-
of DNA technology and where DNA might
tion among law
tors advance through this process, they
be found, the case may have gone
should also keep in mind the array of
enforcement, the
unsolved. The successful review and
other technology advancements, such as
investigation of unsolved cases require
crime laboratory,
improved ballistics and fingerprint databas-
the same basic elements as the investiga-
es, that may benefit their investigation.
and the prosecu-
tion of new cases: cooperation among law
enforcement, the crime laboratory, and
tor’s office.
the prosecutor’s office. Investigators
Advancements in
should be aware of technological
advances in DNA testing that may yield
DNA technology
profiles where previous testing was not
Advancements in DNA analysis, together
performed or was unsuccessful. The
with computer technology and the
crime laboratory can be essential to the
Combined DNA Index System (CODIS),1
preliminary review of unsolved cases, for
have created a powerful crimefighting tool
example, by providing investigators with
for law enforcement. CODIS is a comput-
laboratory reports from previous testing
er network that connects forensic DNA
and consultation regarding the investiga-
laboratories at the local, State, and nation-
tive value of new DNA analysis techniques
al levels. DNA database systems that use
and DNA database search capabilities.
CODIS contain two main criminal indexes
Additionally, the prosecutor’s office should
and a missing persons index. When a
be involved as soon as a case is reopened
DNA profile is developed from crime
so that legal issues are addressed appro-
scene evidence and entered into the
priately. It is also extremely important that
forensic (crime scene) index of CODIS,
case reconstruction considers the victim
the database software searches thou-
or victim’s family and the importance of
sands of convicted offender DNA profiles
finality to closing a case.
2
USING DNA TO SOLVE COLD CASES
(contained in the offender index) of individ-
in unsolved cases by covering the basics
The power of a
uals convicted of offenses such as rape
of DNA analysis and its application to
and murder. Similar to the Automated
forensic casework. The report will also
DNA database
Fingerprint Identification System (AFIS),
demonstrate how DNA database systems,
system is evident
CODIS can aid investigations by efficiently
advancing technology, and cooperative
comparing a DNA profile generated from
efforts can enhance unsolved case inves-
not only in the
biological evidence left at a crime scene
tigative techniques.
success of
against convicted offender DNA profiles
and forensic evidence from other cases
solving crimes
contained in CODIS. CODIS can also aid
New laws
previously thought
investigations by searching the missing
persons index, which contains DNA pro-
Advancements in DNA technology have
unsolvable, but
files of unidentified remains and DNA pro-
led to significant changes in many States’
through the
files of relatives of those who are missing.
statutes, which may affect the manner in
Because of the recidivistic nature of vio-
which unsolved cases are investigated,
prevention
lent offenders, the power of a DNA data-
filed, and prosecuted. Advancements in
of crime.
base system is evident not only in the
the technology have been so significant
success of solving crimes previously
that laws are being created, amended, and
thought unsolvable, but perhaps more
even repealed to take advantage of its
importantly, through the prevention of
ability to identify and convict the guilty and
crime.
exonerate the innocent. Laws regarding
DNA admissibility in court, its use in post-
When properly documented, collected, and
conviction appeals, the creation and
stored, biological evidence can be analyzed
expansion of databases, and the extension
to produce a reliable DNA profile years,
or elimination of statutes of limitation are
even decades, after it is collected. Just as
examples of the quickly evolving impact of
evidence collected from a crime that
DNA on the criminal justice system. Given
occurred yesterday can be analyzed for
the legal changes occurring throughout
DNA, today evidence from an old rape kit,
the country, constant contact and consul-
bloody shirt, or stained bedclothes may
tation with the local prosecutor is critical
contain a valuable DNA profile. These new
not only for the investigation of older
analysis techniques, in combination with an
cases but for all cases in which DNA may
evolving database system, make a powerful
be relevant evidence.
argument for the reevaluation of unsolved
crimes for potential DNA evidence.
Statutes of limitation
Knowledgeable law enforcement officers
Statutes of limitation may be one of the
are taking advantage of powerful DNA
most difficult issues to overcome when
analysis techniques by investigating crime
examining older cases. Statutes of limita-
scenes with a keener eye toward biologi-
tion establish time limits under which
cal evidence. The same new approach
criminal charges can be filed for a particu-
being applied to crime scene processing
lar offense. These statutes are rooted in
and current case investigation can be
the protection of individuals from the use
applied to older unsolved cases. Law
of evidence that becomes less reliable
enforcement agencies across the country
over time. For example, witnesses’ mem-
are establishing cold-case squads to sys-
ories fade as time goes by. However,
tematically review old cases for DNA and
although some evidence, such as eyewit-
other new leads. This report will serve as
ness accounts, can lose credibility over
a resource to assist law enforcement with
time, DNA evidence has the power to
maximizing the potential of DNA evidence
determine truth 10, 15, even 20 years
3
SPECIAL REPORT / JULY 02
after an offense is committed. States are
all convicted felons to submit a DNA pro-
The reliability of
beginning to realize that the reliability of
file to the State database. The tendency
DNA technology
DNA technology may necessitate the
for States to include all convicted felons in
reevaluation of statutes of limitation in the
their databases dramatically increases the
may necessitate
filing of cases.
number of convicted offender DNA pro-
the reevaluation
files against which forensic DNA evidence
of statutes
Database expansion
can be compared, thus making the data-
base system a more powerful tool for law
of limitation.
The use of DNA evidence and convicted
enforcement.
offender DNA databases has expanded
significantly since the first U.S. DNA data-
New legal approaches
base was created in 1989. Although State
and local DNA databases established in
DNA technology and DNA databases have
the early 1990s contained only DNA pro-
encouraged the development of new
files from convicted murderers and sex
approaches to old cases. One such
offenders, the undeniable success of DNA
approach is the filing of charges by “John
databases has resulted in a national trend
Doe” warrant. These warrants are based
toward database expansion. All States
on the unique DNA profile obtained from
require at least some convicted offenders
the analysis of unsolved crime scene evi-
to provide a DNA sample to be collected
dence. Although John Doe warrants are
for DNA profiling and, in 2000, the Federal
traditionally filed based on the physical
Government began requiring certain
description or alias of an unnamed sus-
offenders convicted of Federal or military
pect, investigators and prosecutors are
crimes to also provide a DNA sample for
now filing charges using the suspect’s
the criminal DNA database. Recognizing
DNA profile as the identifier. This innova-
that the effectiveness of the DNA data-
tive approach has allowed charges to be
base relies on the volume of data con-
filed that toll and permit old cases to be
tained in both the forensic index (crime
prosecuted when the person matching the
scene samples) and the convicted offend-
John Doe DNA profile is identified. John
er index of CODIS, many States are
Doe DNA warrants are one way to permit
changing their database statutes to
cases to remain active, allowing them the
include less violent criminals. Many
chance to be solved through the DNA
States are enacting legislation to require
database in the future.
4
The Long and Short of DNA
DNA is the fundamental building block for
standard, it can be determined that it did
an individual’s entire genetic makeup. It is
not come from that known individual.
a component of virtually every cell in the
human body, and a person’s DNA is the
same in every cell. That is, the DNA in a
DNA technology
person’s blood is the same as the DNA in
advancements
his skin cells, saliva, and other biological
material.
Recent advancements in DNA technology
have improved law enforcement’s ability
DNA analysis is a powerful tool because
to use DNA to solve old cases. Original
each person’s DNA is unique (with the
forensic applications of DNA analysis were
exception of identical twins). Therefore,
developed using a technology called
DNA evidence collected from a crime
restriction fragment length polymorphism
scene can implicate or eliminate a sus-
(RFLP). Although very old cases (more
pect, similar to the use of fingerprints. It
than 10 years) may not have had RFLP
also can analyze unidentified remains
analysis done, this kind of DNA testing
through comparisons with DNA from rela-
may have been attempted on more recent
tives. Additionally, when evidence from
unsolved cases. However, because RFLP
one crime scene is compared with evi-
analysis required a relatively large quantity
dence from another using CODIS, those
of DNA, testing may not have been suc-
crime scenes can be linked to the same
cessful. Similarly, biological evidence
perpetrator locally, statewide, and
deemed insufficient in size for testing may
nationally.
not have been previously submitted for
testing. Also, if a biological sample was
DNA is also a powerful tool because when
If biological
degraded by environmental factors such
biological evidence from crime scenes is
as dirt or mold, RFLP analysis may have
evidence is collected and stored properly, forensically
been unsuccessful at yielding a result.
valuable DNA can be found on evidence
available for
Newer technologies could now be suc-
that may be decades old. Therefore, old
cessful in obtaining results.
testing or cases that were previously thought unsolv-
able may contain valuable DNA evidence
retesting in
Newer DNA analysis techniques enable
capable of identifying the perpetrator.
laboratories to develop profiles from bio-
unsolved case
logical evidence invisible to the naked eye,
investigations, it
such as skin cells left on ligatures or
Similar to fingerprints
weapons. Unsolved cases should be eval-
is important that
uated by investigating both traditional and
DNA is often compared with fingerprints
law enforcement
nontraditional sources of DNA. Valuable
in the way matches are determined.
DNA evidence might be available that pre-
and the crime When using either DNA or fingerprints to
viously went undetected in the original
identify a suspect, the evidence collected
laboratory work
investigation.
from the crime scene is compared with a
together to “known” standard. If identifying features
If biological evidence is available for test-
are the same, the DNA or fingerprint can
ing or retesting in unsolved case investiga-
review evidence. be determined to be a match. However, if
tions, it is important that law enforcement
identifying features of the DNA profile or
and the crime laboratory work together
fingerprint are different from the known
to review evidence. Logistical issues
5
SPECIAL REPORT / JULY 02
regarding access to and the cost of DNA
the STR regions that are analyzed for
Fingerprints
DNA Strands
analysis will be a factor, as well as issues
forensic testing intensifies the discrimina-
that relate to the discriminating power of
tion between one DNA profile and anoth-
each technology and that might affect the
er. For example, the likelihood that any
outcome of the results. Laboratory per-
two individuals (except identical twins) will
sonnel can also provide a valuable per-
have the same 13-loci DNA profile can be
spective on which evidence might yield
as high as 1 in 1 billion or greater. The
valuable and probative DNA results.
Federal Bureau of Investigation (FBI) has
Finally, if previously tested biological evi-
chosen 13 specific STR loci to serve as
dence produced a DNA profile but exclud-
the standard for CODIS. The purpose of
ed the original suspect, revisiting those
establishing a core set of STR loci is to
“exclusion” cases in the context of com-
ensure that all forensic laboratories can
paring them with DNA databases might
establish uniform DNA databases and,
prove to be very valuable to solving old
more importantly, share valuable forensic
cases.
information. If the forensic or convicted
offender CODIS index is to be used in the
PCR analysis
investigative stages of unsolved cases,
DNA profiles must be generated by using
PCR (polymerase chain reaction) enhances
STR technology and the specific 13 core
DNA analysis and has enabled laboratories
STR loci selected by the FBI.
to develop DNA profiles from extremely
small samples of biological evidence. The
Mitochondrial DNA analysis
PCR technique replicates exact copies of
DNA contained in a biological evidence
Mitochondrial DNA (mtDNA) analysis
sample without affecting the original,
allows forensic laboratories to develop
If the convicted
much like a copy machine. RFLP analysis
DNA profiles from evidence that may not
offender or
requires a biological sample about the size
be suitable for RFLP or STR analysis.
of a quarter, but PCR can be used to
While RFLP and PCR techniques analyze
forensic index
reproduce millions of copies of the DNA
DNA extracted from the nucleus of a cell,
of CODIS is to
contained in a few skin cells. Since PCR
mtDNA technology analyzes DNA found in
analysis requires only a minute quantity of
a different part of the cell, the mitochon-
be used in the
DNA, it can enable the laboratory to ana-
drion (see exhibit 1). Old remains and evi-
investigative
lyze highly degraded evidence for DNA.
dence lacking nucleated cells—such as
On the other hand, because the sensitive
hair shafts, bones, and teeth—that are
stages of an
PCR technique replicates any and all of
unamenable to STR and RFLP testing may
unsolved case,
the DNA contained in an evidence sample,
yield results if mtDNA analysis is per-
greater attention to contamination issues
formed. For this reason, mtDNA testing
DNA profiles must
is necessary when identifying, collecting,
can be very valuable to the investigation of
be generated
and preserving DNA evidence. These fac-
an unsolved case. For example, a cold
tors may be particularly important in the
case log may show that biological evi-
using STR
evaluation of unsolved cases in which evi-
dence in the form of blood, semen, and
analysis.
dence might have been improperly collect-
hair was collected in a particular case, but
ed or stored.
that all were improperly stored for a long
period of time. Although PCR analysis
STR analysis
sometimes enables the crime laboratory
to generate a DNA profile from very
Short tandem repeat (STR) technology is a
degraded evidence, it is possible that the
forensic analysis that evaluates specific
blood and semen would be so highly
regions (loci) that are found on nuclear
degraded that nuclear DNA analysis would
DNA. The variable (polymorphic) nature of
not yield a DNA profile. However, the hair
6
USING DNA TO SOLVE COLD CASES
shaft could be subjected to mtDNA analy-
Y-chromosome analysis
sis and thus be the key to solving the
case. Finally, it is important to note that all
Several genetic markers have been iden-
maternal relatives (for example, a person’s
tified on the Y chromosome that can
mother or maternal grandmother) have
be used in forensic applications. Y-
identical mtDNA. This enables unidentified
chromosome markers target only the
remains to be analyzed and compared to
male fraction of a biological sample.
the mtDNA profile of any maternal relative
Therefore, this technique can be very
for the purpose of aiding missing persons
valuable if the laboratory detects complex
or unidentified remains investigations.
mixtures (multiple male contributors) with-
Although mtDNA analysis can be very
in a biological evidence sample. Because
valuable to the investigation of criminal
the Y chromosome is transmitted directly
cases, laboratory personnel should always
from a father to all of his sons, it can also
be involved in the process.
be used to trace family relationships
among males. Advancements in Y-chromo-
some testing may eventually eliminate the
need for laboratories to extract and sepa-
Exhibit 1. Cell diagram
rate semen and vaginal cells (for example,
from a vaginal swab of a rape kit) prior to
analysis.
Mitochondrion
Cooperative efforts with the crime labora-
tory are essential to deciding which analy-
sis methods will be most valuable in a
Nucleus
particular case. It is important to note,
however, that while RFLP and mtDNA test-
Chromosomes
ing may be valuable to the investigation of
an old case, current DNA databases are
being populated with DNA profiles that are
generated using STR analysis. RFLP and
mtDNA profiles are not compatible with
the convicted offender or forensic indexes
of CODIS.2
7
How Can DNA Databases
Aid Investigations?
The development and expansion of data-
may be linked to each other, thereby aid-
bases that contain DNA profiles at the
ing an investigation, which may eventually
local, State, and national levels have great-
lead to the identification of a suspect.
ly enhanced law enforcement’s ability to
solve cold cases with DNA. Convicted
offender databases store hundreds of
What is CODIS?
thousands of potential suspect DNA
profiles, against which DNA profiles
CODIS is a computer software program
developed from crime scene evidence
that operates local, State, and national
can be compared.
databases of DNA profiles from convicted
offenders, unsolved crime scene evi-
dence, and missing persons. Every State
in the Nation has a statutory provision for
SUCCESS STORY
the establishment of a DNA database that
A “forensic hit” occurred in the National DNA Index System (NDIS) that linked
allows for the collection of DNA profiles
a dead Florida man’s DNA profile to eight serial unsolved rapes in Washington,
from offenders convicted of particular
D.C. and three offenses in Florida.
crimes. CODIS software enables State,
local, and national law enforcement crime
In 1999, Leon Dundas was killed in a drug deal. Investigators remembered
laboratories to compare DNA profiles elec-
Dundas refusing to give a blood sample in connection with a rape investigation
tronically, thereby linking serial crimes to
in 1998. They were able to obtain Dundas’ blood sample through the medical
each other and identifying suspects by
examiner’s office and forwarded it to the DNA lab at the Florida Department of
matching DNA profiles from crime scenes
Law Enforcement. Dundas’ DNA profile was compared with the national foren-
with profiles from convicted offenders.
sic index and a match was made between Dundas and DNA evidence from a
The success of CODIS is demonstrated by
rape victim in Washington, D.C.
the thousands of matches that have linked
serial cases to each other and cases that
The FBI then entered DNA evidence from additional unsolved rapes committed
have been solved by matching crime
in Washington. Dundas’ DNA matched seven additional rapes in Washington
scene evidence to known convicted
and three more in Jacksonville, Florida. Police in Washington said that without
offenders.
DNA, they would have never identified Dundas, who had no prior recorded his-
tory of violent crime.
The missing persons index consists of the
unidentified persons index and the refer-
Given the recidivistic nature of many
ence index. The unidentified persons
crimes, such as sexual assault and bur-
index contains DNA profiles from recov-
glary, a likelihood exists that the individual
ered remains, such as bone, teeth, or hair.
who committed the crime being investi-
The reference index contains DNA profiles
gated was convicted of a similar crime and
from related individuals of missing per-
already has his or her DNA profile in a
sons so that they can be periodically com-
DNA database that can be searched by
pared to the unidentified persons index.
CODIS. Moreover, CODIS also permits the
All samples for this index are typed using
cross-comparison of DNA profiles devel-
mtDNA and STR DNA analysis (if possible)
oped from biological evidence found at
to maximize the power of advancing
crime scenes. Even if a perpetrator is not
technology.
identified through the database, crimes
9
SPECIAL REPORT / JULY 02
How does CODIS work?
A description of the three CODIS tiers
follows (see exhibit 2).
CODIS uses two indexes to generate
investigative leads in crimes for which bio-
■ Local. Typically, the Local DNA Index
logical evidence is recovered from a crime
System (LDIS) installed at crime labora-
scene. The convicted offender index con-
tories is operated by police departments
tains DNA profiles of individuals convicted
or sheriffs’ offices. DNA profiles origi-
of certain crimes ranging from certain
nated at the local level can be transmit-
misdemeanors to sexual assault and mur-
ted to the State and national levels.
der. Each State has different “qualifying
The offender
offenses” for which persons convicted of
■ State. Each State has a designated labo-
index contains
them must submit a biological sample for
ratory that operates the State DNA
inclusion in the DNA database. The foren-
Index System (SDIS). SDIS allows local
DNA profiles
sic index contains DNA profiles obtained
laboratories within that State to com-
of individuals
from crime scene evidence, such as
pare DNA profiles. SDIS also is the com-
semen, saliva, or blood. CODIS uses
munication path between the local and
convicted of
computer software to automatically
national tiers. SDIS is typically operated
certain crimes.
search across these indexes for a poten-
by the agency responsible for imple-
tial match.
menting and monitoring compliance
The forensic index
with the State’s convicted offender
contains DNA
A match made between profiles in the
statute.
forensic index can link crime scenes to
profiles obtained
each other, possibly identifying serial
■ National. The National DNA Index
from crime
offenders. Based on these “forensic hits,”
System (NDIS) is the highest level of
police in multiple jurisdictions or States
the CODIS hierarchy and enables quali-
scene evidence.
can coordinate their respective investiga-
fied State laboratories that are actively
tions and share leads they have developed
participating in CODIS to compare
independent of each other. Matches made
DNA profiles. NDIS is maintained by
between the forensic and convicted
the FBI under the authority of the DNA
offender indexes can provide investigators
Identification Act of 1994.
with the identity of a suspect(s). It is
important to note that if an “offender hit”
is obtained, that information typically is
Limitations of using the
used as probable cause to obtain a new
DNA database
DNA sample from that suspect so the
match can be confirmed by the crime lab-
The more data contained in the forensic
oratory before an arrest is made.
and offender indexes of CODIS, the more
powerful a tool it becomes for law
LDIS, SDIS, and NDIS
enforcement, especially in its application
to unsolved case investigation. However,
CODIS is implemented as a distributed
because many jurisdictions are in the
database with three hierarchical levels (or
process of developing and populating their
tiers)—local, State, and national. All three
DNA databases, convicted offender and
levels contain forensic and convicted
forensic casework backlogs have been
offender indexes and a population file
created over time and continue to grow
(used to generate statistics). The hierarchi-
for several reasons. First, as States recog-
cal design provides State and local labora-
nize the crime-solving potential of DNA
tories with the flexibility to configure
databases, they continue to expand
CODIS to meet their specific legislative
the scope of their convicted offender
and technical needs.
legislation, which increases the number of
10
USING DNA TO SOLVE COLD CASES
Exhibit 2. CODIS tiers
samples to be collected and analyzed by
that have been collected but have not yet
the DNA laboratory. As a result, more than
been analyzed. Although Federal funding
1 million uncollected convicted offender
has played an important role in reducing
DNA profiles are “owed” to the system.
existing backlogs, the crimefighting poten-
tial of DNA has prompted many States to
An equally important but more difficult
revise their statutes to require nonviolent
problem to quantify is that of unprocessed
convicted offenders to provide a DNA
casework that contains biological evi-
sample for analysis and upload into
dence. This casework backlog may include
CODIS. The trend toward expanding con-
nonsuspect or unsolved cases that could
victed offender DNA statutes to include
be analyzed and solved as a result of
nonviolent offenders has significantly
advancements in DNA technology.
increased the number of DNA samples
requiring collection and analysis. Although
Convicted offender backlogs
the success of using the DNA database as
a crime-solving and crime-prevention tool
Although all 50 States have passed DNA
can easily be demonstrated once convict-
database legislation, many States have
ed offender backlogs are reduced, it
backlogs of convicted offender samples
should be recognized that new backlogs
11
SPECIAL REPORT / JULY 02
are instantly created by the passage of
biological evidence are not being analyzed
expanded DNA legislation laws. Convicted
and entered into the DNA database. In
offender backlogs are an ongoing logistical
many jurisdictions, DNA from crime
issue that can compound the complexity
scenes is still primarily used to prosecute
of investigating cold cases by using the
offenders, not to investigate crimes. The
DNA database.
convicted offender backlog and limited
resources for casework going to trial pre-
Forensic casework backlogs
clude State forensic laboratories from ana-
lyzing all biological evidence for DNA,
Addressing issues that affect the efficient
which in turn prevents law enforcement
and effective use of DNA databases in the
from being able to realize the full crime-
United States is complicated further by
solving potential of CODIS.
the existence of casework backlogs. This
refers to biological evidence in perhaps
The backlog of forensic cases has practical
tens of thousands of criminal cases,
consequences for most law enforcement
including violent and nonviolent crimes,
agencies in the United States. Laboratory
that has not been tested or retested for
capacity limitations result in the ability to
DNA.
process crime scene samples from only
the most serious of offenses. More and
Unprocessed rape kits are a clear example
more, however, agencies such as those in
of this kind of backlog. Despite the estab-
the United Kingdom are discovering the
lished fact that rape typically yields biologi-
value of DNA technology in solving proper-
cal evidence, as of October 1999, at least
ty crimes. Blood left on a broken apart-
180,000 rape kits remained on shelves
ment window or saliva found on a
across the country, unprocessed, because
discarded beer bottle can be used to
no suspects have been identified. The
identify burglars, and the skin cells rubbed
DNA evidence from these and other cri-
off onto the steering wheel of a stolen
minal cases often is not analyzed and
vehicle can solve car thefts. However, as
entered into the DNA database because
long as forensic laboratories remain able
forensic laboratories have to prioritize their
to process only the most serious cases,
work and cases scheduled for trial take
the full potential of DNA technology to
precedence over cases in which no sus-
solve crime will remain untapped.
pect is known. In most jurisdictions, non-
suspect criminal cases that contain
12
Practical Considerations
A broad range of considerations must be
shut as the past form of “sealing.”
made long before any DNA testing is actu-
Multiple items may be sealed in one plas-
ally attempted in older, unsolved cases.
tic bag, or even unpackaged in large,
These include—
open, cardboard boxes. Unprotected
microscope slides from medical facilities
■ Legal considerations, such as the applica-
might also be found as a result of investi-
Local prosecutors
tion or expiration of statutes of limitation.
gating old cases. No attempt should be
made on the part of the investigator to
can provide
■ Technological considerations, such as
separate and repackage evidence. The
the nature and condition of the evidence
valuable insight
condition and position that the evidence
as originally collected, stored, and in
has been stored in could provide valuable
into legal issues.
some instances, subjected to other
clues to the forensic scientist for testabili-
forensic tests.
Victim/witness
ty of evidence. Only when evidence is
found unpackaged should the investigator
units or advocates
■ Practical considerations, such as the
properly package and label the item(s) to
availability of witnesses in the event
can help locate,
minimize the possibility for contamination
DNA testing would identify a suspect
from that point forward. It is important
educate, and
and lead to an arrest and a trial.
that any evidence items are handled mini-
encourage
■ Resource issues, such as the time and
mally and only by individuals wearing dis-
witnesses. Con-
money available for investigation and
posable gloves. As always, it is also very
forensic analysis.
important that all actions taken as a result
sultation with
of opening, evaluating, packaging, or
The nature and scope of these issues
repackaging evidence are documented
representatives
require that any approach to reexamining
thoroughly in the case folder.
from the crime
old cases for potential DNA evidence be
collaborative, whether by an individual
laboratory is
Degraded evidence
investigator or by a specialized unit devel-
critical.
oped specifically for cold case review.
Prior to the frequent use of DNA technolo-
Local prosecutors can provide valuable
gy, biological evidence may have been
insight into legal issues that might prevent
collected and stored in ways that were not
or help a future prosecution. Victim/witness
necessarily the best methods for preserv-
units or advocates can provide valuable
ing samples for future DNA testing. For
assistance with locating, educating, and
example, evidence containing biological
encouraging witnesses. Consultation with
fluids that were originally collected for
representatives from the crime laboratory
ABO Blood Typing analysis or other serolo-
is critical to ensuring that potential DNA
gy methods may have been packaged or
evidence can be successfully analyzed.
stored in ways that can limit DNA testing.
Some methods of collection and storage
may promote the growth of bacteria and
Evidence considerations
mold on the evidence. Bacteria can seri-
ously damage or degrade DNA contained
When collecting unsolved case evidence
in biological material and inhibit the ability
from storage facilities, the case investiga-
to develop a DNA profile; however, evi-
tor should be ready to handle all types of
dence can still sometimes yield DNA
packaging disasters. Evidence may be
results. For example, PCR technology can
stored in heavy-duty plastic bags, stapled
allow the laboratory to develop profiles
13
SPECIAL REPORT / JULY 02
from some moldy biological samples,
It is also important to avoid contamination
whereas other evidence may fail to yield a
when handling biological evidence during
usable DNA profile, even when no mold is
the course of the current review. If evi-
visible. Therefore, close consultation with
dence that may contain biological material
the laboratory is important to determine
is already sealed, do not reopen it before
the type of DNA testing most likely to
sending it to the laboratory. (See Evidence
yield results on the available evidence.
Handling Recommendations.)
Contamination issues
Legal considerations
Because of the particularly sensitive
nature of DNA technology, the potential
Numerous legal issues might arise when
contamination of evidence should be care-
examining older cases for potential DNA
fully considered. Technologies used to
evidence. These issues are most likely
analyze evidence prior to the forensic
jurisdictionally specific and may differ from
application of DNA were not always sensi-
State to State. Although most jurisdictions
tive to contaminants. Evidence in older
maintain no statute of limitation for filing
cases may have been collected in ways
charges in a homicide case, States can
that lacked appropriate contamination or
vary widely in the time allowed for filing
cross-contamination safeguards, which
charges in other cases, such as rape and
can make the DNA results less useful or
other sexual assault crimes. Furthermore,
even misleading. In these cases, clarifying
in recognition of DNA technology’s ability
results by identifying the contributor of an
to solve old cases, many States are
additional profile can determine whether
extending or even eliminating statutes
the DNA results may now be used. When
of limitation for certain crimes.
a mixture is detected, a careful recon-
struction of the evidence collection, stor-
Chain of custody
age, and analysis process must be
undertaken. It may be determined that
When a case remains unsolved for a long
DNA profiles will be required from on-
period of time, evidence is usually handled
scene officers, evidence technicians, or
by an increased number of individuals.
laboratory scientists who had access to
Many unsolved cases to be reviewed for
the evidence for comparison with evi-
DNA evidence may have been previously
dence results. In these instances, proper
reinvestigated or handled by several differ-
chain-of-custody reconstruction is critical.
ent investigators as a result of new leads
or periodic, systematic reviews. Further-
more, as cases age, the likelihood increas-
es that evidence may be moved to new or
EVIDENCE HANDLING RECOMMENDATIONS
remote storage locations as evidence
■ Wear gloves. Change them between handling each item of evidence.
from newer cases fills police department
■
shelves.
Use disposable instruments or clean instruments thoroughly before and
after handling each evidence sample.
Many cases may also have had evidence
■ Avoid touching the area where you believe DNA may exist.
submitted to the laboratory for various
■ Avoid touching your face, nose, and mouth when examining and repackaging
forms of forensic testing. Evidence in
evidence.
older cases may have been submitted for
■ Put dry evidence into new paper bags or envelopes; do not use plastic bags.
standard serological testing, but can now
be tested for DNA with much greater suc-
■ Do not use staples.
cess. Hair previously submitted for stan-
■ If repackaging of evidence is necessary, consult with laboratory personnel.
dard microscopic hair analysis may now
14
USING DNA TO SOLVE COLD CASES
be submitted for mtDNA testing. As with
for up to 7 years after the commission of
It should not be
all criminal investigations, chain-of-custody
the crime. Exceptions also exist for cases
issues are critical to maintaining the
in which child victims are assaulted by a
assumed that
integrity of the evidence. In all cases, the
family member, which can be valuable in
victims and wit-
ultimate ability to use DNA evidence will
the context of a current investigation.
depend on the ability to prove that the
nesses are still
chain of custody was maintained.
interested in pur-
Victim and witness
suing the case.
Statutes of limitation
considerations
Whenever pos-
One of the first issues to address when
Another important consideration to be
reviewing an unsolved case is whether
sible, enlist the
made early in the process is the willing-
the statutes of limitation on a case have
ness of victims and witnesses to proceed.
aid of victim
run out. Several considerations arise when
Although many victims may continuously
addressing a statute of limitation issue.
service providers.
monitor the progress of their investiga-
Good communication between law en-
tions, some choose to detach from the
forcement and local prosecutors is critical
process over time. Reinvestigating a case
when examining these legal questions.
may cause renewed psychological trauma
to the victim and victim’s family. It should
Changes in statutes. Advances in DNA
not be assumed that victims and witness-
technology and the creation of DNA data-
es, even if they were eager to pursue the
bases are leading many criminal justice
case when it occurred, are still interested
professionals to rethink time limits placed
in pursuing the case. A phone call from an
on the filing of criminal charges. Because
investigator years later may not be a wel-
biological evidence can yield reliable DNA
come event. Whenever possible, enlist
analysis results years after the commis-
the aid of victim service providers. If a
sion of a crime, many State legislatures
new officer is handling the investigation,
have begun to extend, and in some
enlisting the assistance of the original
cases eliminate, the statutes of limitation
investigator to make the first contact with
for some crimes and in certain circum-
the victim may also be helpful.
stances. Many States have extended the
length of time for which a complaint can
The older a case is, the more difficult it
be filed, other States have eliminated
may be to locate witnesses. However,
statutes of limitation for certain crimes,
early identification of victim and witness
and some legislation is retroactive.
availability may ultimately save significant
resources. Consultation with prosecutors
Exceptions to statutes. Exceptions often
is mandatory when considering whether a
exist under existing and new statutes.
witness would be necessary at trial.
Under such exceptions, time can be
added to the statute of limitation, giving
police the legal authority to arrest even if
it appears as though the statute has run
STATUTE OF LIMITATION RECOMMENDATIONS
out. For example, many jurisdictions have
■
exceptions for a suspect’s flight from juris-
Know the original statute of limitation.
diction. In a case for which there is a
■ Determine whether the law has changed regarding time limits for filing.
5-year statute of limitation, if the govern-
If so, is the law retroactive?
ment can prove that the suspect has been
■ Determine whether there are exceptions to the statute.
absent from the jurisdiction for 2 years,
■ Consult with the prosecutor.
the State can still file against the suspect
15
Identifying, Analyzing, and
Prioritizing Cases
Whether the process of reviewing
from years ago. In some departments a
Good
unsolved cases is initiated by a single offi-
formalized cold-case unit may systemati-
communication
cer or by a specialized unit, it must ulti-
cally review cases for the potential of DNA
mately be a team effort. At all stages of
testing. Other cases may be identified by
between police,
the process, investigators should avail
coordinated, interdepartmental efforts, vic-
laboratories, and
themselves of the scientific advice of the
tims or witnesses who have heard about
laboratory and the legal expertise of the
the potential of DNA evidence, and labora-
prosecutors can
local prosecutor’s office. Close consulta-
tories taking inventory of their storage
help identify and
tion with the laboratory can ensure that
facilities. If a department is pursuing a sys-
evidence integrity is maintained and that
tematic review of cases, either by one or
convict serious
limited laboratory resources are allocated
two officers or by a formal unit, there are
offenders and save
effectively. Similarly, prosecutors can help
many sources that can be consulted for
identify issues that might occur at trial if a
valuable investigative information, such
valuable time
suspect is identified and arrested upon
as—
and resources.
successful DNA testing. Good communi-
cation between police, laboratories, and
■ Autopsy, laboratory, prosecutor, and
prosecutors can help identify and convict
local agency logbooks.
serious offenders and save valuable time
■
and resources.
Retired investigators.
■ Computer databases.
Identify potential cases
for review
Identify statute of
limitation issues
An initial step in the DNA review of
Statute of limitation issues might affect
unsolved cases is to identify cases that
the ultimate ability to prosecute a case.
might be amenable to DNA testing. While
Cases should be preliminarily reviewed by
the cases considered for this kind of
investigators in conjunction with the pros-
review will vary from jurisdiction to juris-
ecutor’s office to identify which prosecu-
diction, it is important to define minimum
tions would be barred by the statutes of
requirements that will likely benefit from
limitation. If the goal of the unsolved case
this approach. Issues such as statutes of
review program is to obtain convictions
limitation and solvability factors should be
and statutes of limitation have expired on
thoroughly examined in cooperation with a
a particular case, a department may wish
prosecutor and the forensic laboratory to
to save its resources for cases likely to
establish guidelines for case selection. It
yield convictions. However, if the goal
also will be important to identify the ulti-
of the program is to solve and close un-
mate goals of the program so that the
solved cases regardless of whether a con-
selection criteria can be tailored to meet
viction could be obtained, a jurisdiction
those specific goals.
may decide to review all cases that qualify
under its guidelines. This is an important
Cases that could benefit from a review
consideration in the context of investigat-
for potential DNA evidence can be identi-
ing serial offenders whose criminal acts
fied from numerous sources. In some
might span the course of years or
instances a single police officer or investi-
decades.
gator may remember an unsolved case
17
SPECIAL REPORT / JULY 02
Define categories of cases—
■ How many qualifying cases are there?
solvability factors
■ Where are the case files located?
Because the number of cases that qualify
for reinvestigation might be very large, it
■ Are case summaries available?
may be beneficial for a jurisdiction to
define cases according to several solvabili-
■ How many cases will be assigned to
ty factors. Solvability factors include facts
an investigator?
and circumstances of a case that influence
the likelihood that it might be solved
To establish an investigative hierarchy,
through advancements in DNA technolo-
qualifying cases should be reviewed by
gy. For example, a high probability exists
experienced, proficient investigators. A
that analysis of nonsuspect rape kits will
checklist can be used throughout the
yield valuable DNA results. Profiles gener-
review process so that managers can
ated as a result of DNA analysis can now
decide which cases will be worked first.
be entered into CODIS, which can solve a
A checklist can also provide review pro-
case by matching to a convicted offender,
cess consistency throughout the agency.
or aid investigations by linking serial rapes
(See Sample Checklist at the end of this
to each other. Additionally, if an unsolved
report.) The following categories may
murder case contains biological evidence
serve as a model for a hierarchy in priori-
foreign to the victim that did not produce
tizing cases:
viable results from ABO blood typing or
■ There is a known suspect and physical
RFLP DNA analysis, evidence could be
evidence appears to have been pre-
reanalyzed with the more discriminating
served in a manner consistent with suc-
and powerful STR technology. It is also
cessful DNA testing and use of CODIS.
important to recognize and sort out cases
that might not be as likely to be solved
■ There is no known suspect but physical
with DNA technology. An example might
evidence has been preserved in a man-
be an unsolved drive-by homicide because
ner consistent with successful DNA
the perpetrator most likely would not have
testing and use of CODIS.
left biological evidence at this kind of
crime scene.
■ There is no known suspect and evi-
dence was collected and preserved in
a manner that may make it difficult to
Case review—
obtain a DNA profile.
establish priorities
Once solvability factors and statute of limi-
Locating case files,
tation issues are addressed, it is important
obtaining evidence logs,
to continue the process by identifying the
cases to be reviewed first. To preserve
and other documentation
investigative resources when considering
Locating the case file and original evidence
a larger number of unsolved cases for
for the investigation may be a challenging
review, jurisdictions may prioritize accord-
endeavor. Changes in personnel, proce-
ing to the likelihood that cases will be
dure, and facilities and the passage of
solved or the likelihood that investigations
time may complicate the process. When
will be aided. In establishing this priority,
searching for a case file or evidence, an
the following criteria can be considered:
investigator may need to look in numerous
18
USING DNA TO SOLVE COLD CASES
places. Potential locations include, but are
memorialize proper chain of custody.
not limited to, the following:
Cooperation with the crime laboratory is
crucial to locate and interpret existing
■ Police department property rooms (case
forensic reports and to determine whether
files, evidence logs, whole evidence).
evidence would be amenable to reanalysis
with new DNA techniques.
■ Property warehouses (case files, evi-
dence logs, whole evidence).
Many combinations of options are avail-
able to investigators and laboratory per-
■ Public crime laboratories (previously
sonnel if biological evidence was available
tested/submitted evidence, lab reports).
and previously tested. Exhibit 3 may serve
to help investigators as they work with the
■ Private laboratories (previously tested
laboratory to discuss options throughout
evidence, lab reports).
the course of the investigation.
■ Hospital/medical facilities (rape kits,
medical reports, slides).
Locate biological evidence
■ Coroner/medical examiners’ offices
When reviewing the case file for potential
(autopsy reports).
DNA evidence, it is important to know
what kinds of evidence may yield a DNA
■ Courthouse property rooms.
profile. Given the power and sensitivity of
newer DNA testing techniques, DNA can
■ Prosecutors’ offices (previous trial or
be collected from virtually anywhere. Only
suspect investigation).
a few cells can be sufficient to obtain use-
ful DNA information to help solve a case.
■ Retired investigators’ files (case notes
Exhibit 4 identifies some common items of
and details not contained in file).
evidence that may have been collected pre-
viously but not analyzed for the presence
■ Other investigating agency offices
of DNA evidence. Remember, if a stain is
(investigative leads—serial offender).
not visible it does not mean that there are
not enough cells for DNA typing. Further,
Forensic testing reports and
DNA does more than just identify the
previously tested evidence
source of the sample; it can place a known
individual at a crime scene, in a home, or in
Because advancements in DNA technolo-
a room where the suspect claimed not to
gy enable laboratories to successfully ana-
have been. It can refute a claim of self-
lyze old evidence that might have been
defense and put a weapon in the suspect’s
improperly stored or subjected to previous
forensic analysis, it will be very valuable to
locate any and all forensic reports that
were produced as a result of previous
DNA CAN DO MORE . . .
analysis and/or testing. ABO blood typing,
. . . than identify a suspect. It can also—
microscopic hair analysis, RFLP DNA
analysis, or fingerprint analysis (among
■ Place a known individual at a crime scene.
others) might have been performed in the
■ Refute a claim of self-defense.
course of the original investigation. The
■ Put a weapon in a suspect’s hand.
original case file should indicate whether
and which types of forensic analysis were
■ Change a suspect’s story from an alibi to one of consent.
attempted. These reports also serve to
19
SPECIAL REPORT / JULY 02
hand. It can also provide irrefutable evi-
gation on cooperative efforts between the
dence that can change a suspect’s story
laboratory and prosecutor can save valu-
from an alibi to one of consent.
able resources, develop leads, and identify
previously overlooked evidence that may
yield a DNA profile.
Evaluate for probative
DNA evidence
Continue investigative
On completion of reviewing the case file,
protocol
reports, and evidence in consultation with
the laboratory, it will be necessary to iden-
If DNA analysis is to be conducted, it may
tify which evidentiary items will be
be important to obtain reference samples
amenable to DNA analysis. Consultation
from prior suspects, and it might be nec-
with the laboratory will be essential to
essary to be creative when obtaining
determine the likelihood of obtaining
these samples. While a biological sample
results from DNA analysis, and consulta-
in the form of blood or saliva can be
tion with a prosecutor is very important to
obtained voluntarily through a consent
determine which evidence will be proba-
form, a standard reference sample might
tive to the case. Building the new investi-
already exist if previous forensic analysis,
Exhibit 3. Investigative options
Test conducted
Original results
Original interpretation
Options for investigators
RFLP/PCR
Obtained profiles.
No suspects identified.
Is the original extract remaining?
1. If so, retest using STR technique and
submit to CODIS.
2. If not, reextract the original sample
using STR technique and submit to
CODIS.
RFLP
Inconclusive or no results obtained.
Sample size may have been
Is the original extract remaining?
insufficient or not concentrated
1. If so, retest using STR technique and
enough.
submit to CODIS.
2. If not, reextract the original sample
using STR technique and submit to
CODIS.
PCR
Inconclusive or result intensity
Sample size may have been
Is the original extract remaining?
below “S” and “C” dots.
insufficient.
1. If so, retest using STR technique and
submit to CODIS.
2. If not, reextract the original sample
using STR technique and submit to
CODIS.
Conventional serology (ABO, secretor
Obtained a type in these systems.
Poor statistics and no searching
If original evidence still exists, extract
status, enzymes such as EsD, PGM,
capability.
the sample using STR technique and
GLO I, EAP, ADA, AK).
submit to CODIS.
None
1. Limited sample size.
If original evidence still exists, extract
2. No suspects, did not process
the sample using STR technique and
further.
submit to CODIS.
3. No request at the time of
analysis.
20
USING DNA TO SOLVE COLD CASES
such as serological testing, was per-
Follow agency procedures
formed during the course of the original
for submitting the DNA
investigation.
profile to CODIS
Additionally, elimination samples from any-
one who had lawful access to the crime
On successful laboratory analysis resulting
scene, such as family members, may be
in a DNA profile developed from crime
required if the laboratory determines that
scene evidence, existing and/or new sus-
there is more than one DNA profile pres-
pect DNA profiles should be compared
ent in the evidence sample. Early identi-
with the evidence profile. If the laboratory
fication of the location and status of
determines a match between a suspect
persons who might be requested to sub-
and the evidence, the prosecutor’s office
mit an elimination sample could save valu-
should be consulted on how to proceed.
able time and resources if the laboratory
However, if a match is not found, agency
needs such information. Consultation with
procedures should be followed, in accor-
the laboratory is essential to properly coor-
dance with the crime laboratory, to submit
dinating this process.
the crime scene evidence DNA profile into
CODIS.
Exhibit 4. Common items of evidence
Evidence
Possible location of DNA on the evidence
Source of DNA
Baseball bat
Handle
Skin cells, sweat, blood, tissue
Hat, bandanna, or mask
Inside surfaces
Sweat, hair, skin cells, dandruff, saliva
Eyeglasses
Nose or ear piece, lens
Sweat, skin cells
Facial tissue, cotton swab
Surface
Mucus, blood, sweat, semen, ear wax
Dirty laundry
Surface
Blood, sweat, semen, saliva
Toothpick
Surface
Saliva
Used cigarette
Cigarette butt (filter area)
Saliva
Used stamp/envelope seal
Moistened area
Saliva
Tape or ligature
Inside or outside surface
Skin cells, sweat, saliva
Bottle, can, or glass
Mouthpiece, rim, outer surface
Saliva, sweat, skin cells
Used condom
Inside/outside surface
Semen, vaginal or rectal cells
Bed linens
Surface
Sweat, hair, semen, saliva, blood
“Through and through” bullet
Outside surface
Blood, tissue
Bite mark
Surface of skin
Saliva
Fingernail/partial fingernail
Scrapings
Blood, sweat, tissue, skin cells
Note: When reviewing evidence, it is important to maintain chain of custody, consult with laboratory personnel, and take all appropriate precautions against contamination,
including wearing gloves and changing them between handling of different pieces of evidence.
21
SPECIAL REPORT / JULY 02
Because CODIS contains hundreds of
have statute of limitation issues that might
thousands of convicted offender DNA pro-
prevent the prosecution of the case if a
files, it is possible that the person who
match is not determined in a timely man-
committed the unsolved crime being
ner. Therefore, if no offender match
investigated was convicted of a qualifying
occurs in cases in which statutes of limita-
offense that required submission of a
tion are an issue, consideration may be
DNA profile to the database. If that person
given, in consultation with the prosecutor,
has not previously been convicted of a
to preparing a John Doe warrant. These
qualifying offense, especially in light of
types of warrants can identify the perpe-
expanding database law, it is possible that
trator according to his or her DNA profile.
they will be convicted in the future.
The 13-loci profile generated by the crime
Further, because the forensic index of
laboratory should be clearly printed on the
CODIS contains thousands of crime scene
face of the warrant. The John Doe warrant
evidence profiles, the investigation could
is not novel; however, the unconventional
be aided if a match is made to another
method of describing an individual by his
forensic DNA profile already in the data-
or her DNA profile may allow for pros-
base. Finally, an investigator should not
ecution of a case if a DNA match is
assume that a new DNA profile generated
determined in the course of future investi-
from unsolved case evidence and submit-
gations or as a result of the CODIS sys-
ted to the laboratory for entry into CODIS
tem being populated with more convicted
will be compared with every possible con-
offender and forensic DNA profiles.
victed offender or crime scene index pro-
file. The investigator may need to
proactively request that his CODIS admin-
Notes
istrator search the new profile against the
local, State, and national DNA databases.
1. CODIS uses two indexes—the forensic index and
the offender index—to generate investigative leads
in crimes where biological evidence is recovered
from crime scenes. The forensic index contains DNA
Prepare a John Doe warrant
profiles of biological crime scene evidence and the
offender index contains DNA profiles of individuals
CODIS is a powerful crime-solving and
convicted of a qualifying offense.
crime-prevention tool, but many cases will
2. CODIS has a missing persons index that exclusive-
not be solved as a result of entering a
ly contains mtDNA profiles; the convicted offender
DNA profile into the forensic index of the
and forensic indexes of CODIS exclusively contain
database. Additionally, many cases will
STR DNA profiles.
22
USING DNA TO SOLVE COLD CASES
SAMPLE CHECKLIST
■ Identify potential cases.
■ Identify any statute of limitation issues (consult with prosecutors).
■ Define case categories according to solvability factors.
■ Prioritize cases (consider solvability factors).
■ Locate and review the case file; obtain evidence logs and other documentation
such as laboratory and autopsy reports.
■ Locate previous forensic testing reports and location of previously tested evidence.
For example—
■ Blood previously ABO typed.
■ Hair analyzed microscopically.
■ Fingerprint evidence.
■ Locate crime scene evidence containing biological material.
■ Evaluate the case and evidence for potential probative DNA. Be sure to—
■ Consider all evidentiary possibilities.
■ Take appropriate precautions against contamination.
■ In consultation with the laboratory and prosecutors, submit appropriate (probative)
evidence to the laboratory for testing.
■ Continue investigative protocol. If needed, obtain reference samples from suspects—
■ Voluntarily using a consent form.
■ By using a previously obtained sample (e.g., if a reference sample was used
for standard serological testing).
■ Identify witness issues—
■ Legal availability.
■ Willingness to proceed.
■ Location.
■ If a profile does not match suspect profiles, follow agency procedures for submitting the
evidence profile to CODIS.
■ If no offender match occurs in cases in which statutes of limitation are an issue, prepare
a John Doe warrant.
23
About the National Institute of Justice
NIJ is the research, development, and evaluation agency of the U.S. Department of Justice and
is solely dedicated to researching crime control and justice issues. NIJ provides objective, inde-
pendent, nonpartisan, evidence-based knowledge and tools to meet the challenges of crime and
justice, particularly at the State and local levels. NIJ’s principal authorities are derived from the
Omnibus Crime Control and Safe Streets Act of 1968, as amended (42 U.S.C. §§ 3721–3722).
NIJ’s Mission
In partnership with others, NIJ’s mission is to prevent and reduce crime, improve law enforcement
To find out more about the National
and the administration of justice, and promote public safety. By applying the disciplines of the
Institute of Justice, please contact:
social and physical sciences, NIJ—
National Criminal Justice
• Researches the nature and impact of crime and delinquency.
Reference Service
• Develops applied technologies, standards, and tools for criminal justice practitioners.
P.O. Box 6000
• Evaluates existing programs and responses to crime.
Rockville, MD 20849–6000
• Tests innovative concepts and program models in the field.
800–851–3420
• Assists policymakers, program partners, and justice agencies.
e-mail: askncjrs@ncjrs.org
• Disseminates knowledge to many audiences.
NIJ’s Strategic Direction and Program Areas
NIJ is committed to five challenges as part of its strategic plan: 1) rethinking justice and the
processes that create just communities; 2) understanding the nexus between social conditions
and crime; 3) breaking the cycle of crime by testing research-based interventions; 4) creating the
tools and technologies that meet the needs of practitioners; and 5) expanding horizons through
interdisciplinary and international perspectives. In addressing these strategic challenges, the
Institute is involved in the following program areas: crime control and prevention, drugs and
crime, justice systems and offender behavior, violence and victimization, communications and
information technologies, critical incident response, investigative and forensic sciences (includ-
ing DNA), less-than-lethal technologies, officer protection, education and training technologies,
testing and standards, technology assistance to law enforcement and corrections agencies, field
testing of promising programs, and international crime control. NIJ communicates its findings
through conferences and print and electronic media.
NIJ’s Structure
The NIJ Director is appointed by the President and confirmed by the Senate. The NIJ Director
establishes the Institute’s objectives, guided by the priorities of the Office of Justice Programs,
the U.S. Department of Justice, and the needs of the field. NIJ actively solicits the views of crimi-
nal justice and other professionals and researchers to inform its search for the knowledge and
tools to guide policy and practice.
NIJ has three operating units. The Office of Research and Evaluation manages social science
research and evaluation and crime mapping research. The Office of Science and Technology
manages technology research and development, standards development, and technology assis-
tance to State and local law enforcement and corrections agencies. The Office of Development
and Communications manages field tests of model programs, international research, and knowl-
edge dissemination programs. NIJ is a component of the Office of Justice Programs, which also
includes the Bureau of Justice Assistance, the Bureau of Justice Statistics, the Office of Juvenile
Justice and Delinquency Prevention, and the Office for Victims of Crime.
U.S. Department of Justice
Office of Justice Programs
National Institute of Justice
JUL
Washington, DC 20531
Official Business
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Penalty for Private Use $300
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NCJ 194197
