| Copyright © 2006 - 2008 - Barry M. Baker - CareerPoliceOfficer.com |
| Disclaimer |
| CareerPoliceOfficer.com is not responsible for the contents of any linked site or any link contained in a linked site, or any changes or updates to such sites. Links are provided only as a convenience, and the inclusion of any link does not imply endorsement by this site. |
 | |  | |  | |  | |  | |  |
 | |  | |  | |  | |  | |  |
| DNA |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
| |
 |
How does forensic identification work?
Any type of organism can be identified by examination of DNA
sequences unique to that species. Identifying individuals within a
species is less precise at this time, although when DNA sequencing
technologies progress farther, direct comparison of very large DNA
segments, and possibly even whole genomes, will become feasible and
practical and will allow precise individual identification.
To identify individuals, forensic scientists scan 13 DNA regions that
vary from person to person and use the data to create a DNA profile of
that individual (sometimes called a DNA fingerprint). There is an
extremely small chance that another person has the same DNA profile
for a particular set of regions.
Some Examples of DNA Uses for Forensic Identification
-Identify potential suspects whose DNA may match evidence left at
crime scenes
-Exonerate persons wrongly accused of crimes
-Identify crime and catastrophe victims
-Establish paternity and other family relationships
-Identify endangered and protected species as an aid to wildlife
officials (could be used for prosecuting poachers)
-Detect bacteria and other organisms that may pollute air, water, soil,
and food
-Match organ donors with recipients in transplant programs
-Determine pedigree for seed or livestock breeds
-Authenticate consumables such as caviar and wine
Is DNA effective in identifying persons?
[answer provided by Daniel Drell of the U.S. DOE Human Genome
Program]
DNA identification can be quite effective if used intelligently. Portions of
the DNA sequence that vary the most among humans must be used;
also, portions must be large enough to overcome the fact that human
mating is not absolutely random.
Consider the scenario of a crime scene investigation . . .
Assume that type O blood is found at the crime scene. Type O occurs
in about 45% of Americans. If investigators type only for ABO, then
finding that the "suspect" in a crime is type O really doesn't reveal very
much.
If, in addition to being type O, the suspect is a blond, and blond hair is
found at the crime scene, then you now have two bits of evidence to
suggest who really did it. However, there are a lot of Type O blonds
out there.
If you find that the crime scene has footprints from a pair of Nike Air
Jordans (with a distinctive tread design) and the suspect, in addition to
being type O and blond, is also wearing Air Jordans with the same
tread design, then you are much closer to linking the suspect with the
crime scene.
In this way, by accumulating bits of linking evidence in a chain, where
each bit by itself isn't very strong but the set of all of them together is
very strong, you can argue that your suspect really is the right person.
With DNA, the same kind of thinking is used; you can look for matches
(based on sequence or on numbers of small repeating units of DNA
sequence) at a number of different locations on the person's genome;
one or two (even three) aren't enough to be confident that the suspect
is the right one, but four (sometimes five) are used and a match at all
five is rare enough that you (or a prosecutor or a jury) can be very
confident ("beyond a reasonable doubt") that the right person is
accused.
How is DNA typing done?
Only one-tenth of a single percent of DNA (about 3 million bases)
differs from one person to the next. Scientists can use these variable
regions to generate a DNA profile of an individual, using samples from
blood, bone, hair, and other body tissues and products.
In criminal cases, this generally involves obtaining samples from crime-
scene evidence and a suspect, extracting the DNA, and analyzing it for
the presence of a set of specific DNA regions (markers).
Scientists find the markers in a DNA sample by designing small pieces
of DNA (probes) that will each seek out and bind to a complementary
DNA sequence in the sample. A series of probes bound to a DNA
sample creates a distinctive pattern for an individual. Forensic
scientists compare these DNA profiles to determine whether the
suspect's sample matches the evidence sample. A marker by itself
usually is not unique to an individual; if, however, two DNA samples are
alike at four or five regions, odds are great that the samples are from
the same person.
If the sample profiles don't match, the person did not contribute the
DNA at the crime scene.
If the patterns match, the suspect may have contributed the evidence
sample. While there is a chance that someone else has the same DNA
profile for a particular probe set, the odds are exceedingly slim. The
question is, How small do the odds have to be when conviction of the
guilty or acquittal of the innocent lies in the balance? Many judges
consider this a matter for a jury to take into consideration along with
other evidence in the case. Experts point out that using DNA forensic
technology is far superior to eyewitness accounts, where the odds for
correct identification are about 50:50.
The more probes used in DNA analysis, the greater the odds for a
unique pattern and against a coincidental match, but each additional
probe adds greatly to the time and expense of testing. Four to six
probes are recommended. Testing with several more probes will
become routine, observed John Hicks (Alabama State Department of
Forensic Services). He predicted that, DNA chip technology (in which
thousands of short DNA sequences are embedded in a tiny chip) will
enable much more rapid, inexpensive analysis using many more
probes, and raising the odds against coincidental matches.
What are some of the DNA technologies used in forensic
investigations?
Restriction Fragment Length Polymorphism (RFLP)
RFLP is a technique for analyzing the variable lengths of DNA
fragments that result from digesting a DNA sample with a special kind
of enzyme. This enzyme, a restriction endonuclease, cuts DNA at a
specific sequence pattern know as a restriction endonuclease
recognition site. The presence or absence of certain recognition sites
in a DNA sample generates variable lengths of DNA fragments, which
are separated using gel electrophoresis. They are then hybridized with
DNA probes that bind to a complementary DNA sequence in the
sample.
RFLP is one of the original applications of DNA analysis to forensic
investigation. With the development of newer, more efficient DNA-
analysis techniques, RFLP is not used as much as it once was
because it requires relatively large amounts of DNA. In addition,
samples degraded by environmental factors, such as dirt or mold, do
not work well with RFLP.
PCR Analysis
PCR (polymerase chain reaction) is used to make millions of exact
copies of DNA from a biological sample. DNA amplification with PCR
allows DNA analysis on biological samples as small as a few skin cells.
With RFLP, DNA samples would have to be about the size of a quarter.
The ability of PCR to amplify such tiny quantities of DNA enables even
highly degraded samples to be analyzed. Great care, however, must
be taken to prevent contamination with other biological materials
during the identifying, collecting, and preserving of a sample.
STR Analysis
Short tandem repeat (STR) technology is used to evaluate specific
regions (loci) within nuclear DNA. Variability in STR regions can be
used to distinguish one DNA profile from another. The Federal Bureau
of Investigation (FBI) uses a standard set of 13 specific STR regions
for CODIS. CODIS is a software program that operates local, state,
and national databases of DNA profiles from convicted offenders,
unsolved crime scene evidence, and missing persons. The odds that
two individuals will have the same 13-loci DNA profile is about one in
one billion.
Mitochondrial DNA Analysis
Mitochondrial DNA analysis (mtDNA) can be used to examine the DNA
from samples that cannot be analyzed by RFLP or STR. Nuclear DNA
must be extracted from samples for use in RFLP, PCR, and STR;
however, mtDNA analysis uses DNA extracted from another cellular
organelle called a mitochondrion. While older biological samples that
lack nucleated cellular material, such as hair, bones, and teeth, cannot
be analyzed with STR and RFLP, they can be analyzed with mtDNA. In
the investigation of cases that have gone unsolved for many years,
mtDNA is extremely valuable.
All mothers have the same mitochondrial DNA as their daughters. This
is because the mitochondria of each new embryo comes from the
mother's egg cell. The father's sperm contributes only nuclear DNA.
Comparing the mtDNA profile of unidentified remains with the profile of
a potential maternal relative can be an important technique in missing
person investigations.
Y-Chromosome Analysis
The Y chromosome is passed directly from father to son, so the
analysis of genetic markers on the Y chromosome is especially useful
for tracing relationships among males or for analyzing biological
evidence involving multiple male contributors.
The answer to this question is based on information from Using DNA to
Solve Cold Cases - A special report from the National Institute of
Justice (July 2002).
Some Interesting Uses of DNA Forensic Identification
Son of Louis XVI and Marie Antionette
PARIS, Apr 19, 2000 (Reuters) -- Scientists cracked one of the great
mysteries of European history by using DNA tests to prove that the son
of executed French King Louis XVI and Marie-Antoinette died in prison
as a child. Royalists have argued for 205 years over whether Louis-
Charles de France perished in 1795 in a grim Paris prison or managed
to escape the clutches of the French Revolution. In December 1999,
the presumed heart of the child king was removed from its resting
place to enable scientists to compare its DNA make-up with samples
from living and dead members of the royal family -- including a lock of
his mother Marie-Antoinette's hair.
Super Bowl XXXIV footballs and 2000 Summer Olympic souvenirs
The NFL used DNA technology to tag all of the Super Bowl XXXIV balls,
ensuring their authenticity for years to come and helping to combat the
growing epidemic of sports memorabilia fraud. The footballs were
marked with an invisible, yet permanent, strand of synthetic DNA. The
DNA strand is unique and is verifiable any time in the future using a
specially calibrated laser.
A section of human genetic code taken from several unnamed
Australian athletes was added to ink used to mark all official goods —
everything from caps to socks — from the 2000 Summer Olympic
Games. The technology is used as a way to mark artwork or one-of-a-
kind sports souvenirs.
Snowball the Cat
A woman was murdered in Prince Edward Island, Canada. Her
estranged husband was implicated because a snowy white cat hair was
found in a jacket near the scene of the crime, and DNA fragments from
the hair matched DNA fragments from Snowball, the cat belonging to
the husband's parents. M. Menotti-Raymond et al., "Pet cat hair
implicates murder suspect," Nature, 386: 774, 1997.
Angiosperm Witness for the Prosecution
The first case in which a murderer was convicted on DNA evidence
obtained from a plant was described in the PBS TV series, "Scientific
American Frontiers." A young woman was murdered in Phoenix,
Arizona, and a pager found at the scene of the crime led the police to
a prime suspect. He admitted picking up the victim, but claimed she
had robbed him of his wallet and pager. The forensic squad examined
the suspect's pickup truck and collected pods later identified as the
fruits of the palo verde tree (Cercidium spp.). One detective went back
to the murder scene and found several Palo Verde trees, one of which
showed damage that could have been caused by a vehicle. The
detective's superior officer innocently suggested the possibility of
linking the fruits and the tree by using DNA comparison, not realizing
that this had never been done before. Several researchers were
contacted before a geneticist at the University of Arizona in Tucson
agreed to take on the case. Of course, it was crucial to establish
evidence that would stand up in court on whether individual plants
(especially Palo Verde trees) have unique patterns of DNA. A
preliminary study on samples from different trees at the murder scene
and elsewhere quickly established that each Palo Verde tree is unique
in its DNA pattern. It was then a simple matter to link the pods from the
suspect's truck to the damaged tree at the murder scene and obtain a
conviction. [WNED-TV (PBS - Buffalo, N.Y.)]
DNA Forensics Databases
National DNA Databank: CODIS
CODIS: Combined DNA Index System
The COmbined DNA Index System, CODIS, blends computer and DNA
technologies into a tool for fighting violent crime. The current version
of CODIS uses two indexes to generate investigative leads in crimes
where biological evidence is recovered from the crime scene. The
Convicted Offender index contains DNA profiles of individuals
convicted of felony sex offenses (and other violent crimes). The
Forensic index contains DNA profiles developed from crime scene
evidence. All DNA profiles stored in CODIS are generated using STR
(short tandem repeat) analysis.
CODIS utilizes computer software to automatically search its two
indexes for matching DNA profiles. Law enforcement agencies at
federal, state, and local levels take DNA from biological evidence (e.g.,
blood and saliva) gathered in crimes that have no suspect and
compare it to the DNA in the profiles stored in the CODIS systems. If a
match is made between a sample and a stored profile, CODIS can
identify the perpetrator.
This technology is authorized by the DNA Identification Act of 1994. All
50 states have laws requiring that DNA profiles of certain offenders be
sent to CODIS. As of January 2003, the database contained more than
a million DNA profiles in its Convicted Offender Index and about 48,000
DNA profiles collected from crime scenes but which have not been
connected to a particular offender.
As more offender DNA samples are collected and law enforcement
becomes better trained and equipped to collect DNA samples at crime
scenes, the backlog of samples awaiting testing throughout the
criminal justice system has increased dramatically. In March 2003
President Bush proposed $1 billion in funding over 5 years to reduce
the DNA testing backlog, build crime lab capacity, stimulate research
and development, support training, protect the innocent, and identify
missing persons. For more information, seethe U.S. Department of
Justice's Advancing Justice Through DNA Technology.
Ethical, Legal, and Social Concerns about DNA
Databanking
The primary concern is privacy. DNA profiles are different from
fingerprints, which are useful only for identification. DNA can provide
insights into many intimate aspects of a person and their families
including susceptibility to particular diseases, legitimacy of birth, and
perhaps predispositions to certain behaviors and sexual orientation.
This increases the potential for genetic discrimination by government,
insurers, employers, schools, banks, and others.
Collected samples are stored, and many state laws do not require the
destruction of a DNA record or sample after a conviction has been
overturned. So there is a chance that a person's entire genome may
be available --criminal or otherwise. Although the DNA used is
considered "junk DNA" (STRs-single tandem repeated DNA bases), in
the future this information may be found to reveal personal information
such as susceptibilities to disease and certain behaviors.
Who is chosen for sampling is also a concern. In the United Kingdom,
for example, all suspects can be forced to provide a DNA sample.
Likewise, all arrestees --regardless of the degree of the charge and
the possibility that they may not be convicted--can be compelled to
comply. This empowers police officers, rather than judges and juries,
to provide the state with intimate evidence that could lead to
"investigative arrests." In the U.S., arresting people on less than
probable cause just to obtain DNA evidence raises the question of
Fourth Amendment violations against unreasonable search and
seizure.
Practicality also is a concern. An enormous backlog of over half a
million DNA samples waits to be entered into the CODIS system. The
statute of limitations has expired in many cases where the evidence
would have been useful for conviction .
Potential Benefits of DNA Databanking Arrestees
(According to Howard Safir, NYC Police Commissioner, 1999)
-Most major crimes involve people who also have committed minor
offenses.
-Innocent people currently are incarcerated for crimes they did not
commit; if samples had been taken at the time of arrest, these
individuals would have been excluded early in the investigative
process.
-Moving the point of testing from conviction to arrest would result in
savings in investigation, prosecution, and incarceration.
-Investigators would be able to compare other cases against the
arrested person's DNA profile, just as with fingerprints.
Any type of organism can be identified by examination of DNA
sequences unique to that species. Identifying individuals within a
species is less precise at this time, although when DNA sequencing
technologies progress farther, direct comparison of very large DNA
segments, and possibly even whole genomes, will become feasible and
practical and will allow precise individual identification.
To identify individuals, forensic scientists scan 13 DNA regions that
vary from person to person and use the data to create a DNA profile of
that individual (sometimes called a DNA fingerprint). There is an
extremely small chance that another person has the same DNA profile
for a particular set of regions.
Some Examples of DNA Uses for Forensic Identification
-Identify potential suspects whose DNA may match evidence left at
crime scenes
-Exonerate persons wrongly accused of crimes
-Identify crime and catastrophe victims
-Establish paternity and other family relationships
-Identify endangered and protected species as an aid to wildlife
officials (could be used for prosecuting poachers)
-Detect bacteria and other organisms that may pollute air, water, soil,
and food
-Match organ donors with recipients in transplant programs
-Determine pedigree for seed or livestock breeds
-Authenticate consumables such as caviar and wine
Is DNA effective in identifying persons?
[answer provided by Daniel Drell of the U.S. DOE Human Genome
Program]
DNA identification can be quite effective if used intelligently. Portions of
the DNA sequence that vary the most among humans must be used;
also, portions must be large enough to overcome the fact that human
mating is not absolutely random.
Consider the scenario of a crime scene investigation . . .
Assume that type O blood is found at the crime scene. Type O occurs
in about 45% of Americans. If investigators type only for ABO, then
finding that the "suspect" in a crime is type O really doesn't reveal very
much.
If, in addition to being type O, the suspect is a blond, and blond hair is
found at the crime scene, then you now have two bits of evidence to
suggest who really did it. However, there are a lot of Type O blonds
out there.
If you find that the crime scene has footprints from a pair of Nike Air
Jordans (with a distinctive tread design) and the suspect, in addition to
being type O and blond, is also wearing Air Jordans with the same
tread design, then you are much closer to linking the suspect with the
crime scene.
In this way, by accumulating bits of linking evidence in a chain, where
each bit by itself isn't very strong but the set of all of them together is
very strong, you can argue that your suspect really is the right person.
With DNA, the same kind of thinking is used; you can look for matches
(based on sequence or on numbers of small repeating units of DNA
sequence) at a number of different locations on the person's genome;
one or two (even three) aren't enough to be confident that the suspect
is the right one, but four (sometimes five) are used and a match at all
five is rare enough that you (or a prosecutor or a jury) can be very
confident ("beyond a reasonable doubt") that the right person is
accused.
How is DNA typing done?
Only one-tenth of a single percent of DNA (about 3 million bases)
differs from one person to the next. Scientists can use these variable
regions to generate a DNA profile of an individual, using samples from
blood, bone, hair, and other body tissues and products.
In criminal cases, this generally involves obtaining samples from crime-
scene evidence and a suspect, extracting the DNA, and analyzing it for
the presence of a set of specific DNA regions (markers).
Scientists find the markers in a DNA sample by designing small pieces
of DNA (probes) that will each seek out and bind to a complementary
DNA sequence in the sample. A series of probes bound to a DNA
sample creates a distinctive pattern for an individual. Forensic
scientists compare these DNA profiles to determine whether the
suspect's sample matches the evidence sample. A marker by itself
usually is not unique to an individual; if, however, two DNA samples are
alike at four or five regions, odds are great that the samples are from
the same person.
If the sample profiles don't match, the person did not contribute the
DNA at the crime scene.
If the patterns match, the suspect may have contributed the evidence
sample. While there is a chance that someone else has the same DNA
profile for a particular probe set, the odds are exceedingly slim. The
question is, How small do the odds have to be when conviction of the
guilty or acquittal of the innocent lies in the balance? Many judges
consider this a matter for a jury to take into consideration along with
other evidence in the case. Experts point out that using DNA forensic
technology is far superior to eyewitness accounts, where the odds for
correct identification are about 50:50.
The more probes used in DNA analysis, the greater the odds for a
unique pattern and against a coincidental match, but each additional
probe adds greatly to the time and expense of testing. Four to six
probes are recommended. Testing with several more probes will
become routine, observed John Hicks (Alabama State Department of
Forensic Services). He predicted that, DNA chip technology (in which
thousands of short DNA sequences are embedded in a tiny chip) will
enable much more rapid, inexpensive analysis using many more
probes, and raising the odds against coincidental matches.
What are some of the DNA technologies used in forensic
investigations?
Restriction Fragment Length Polymorphism (RFLP)
RFLP is a technique for analyzing the variable lengths of DNA
fragments that result from digesting a DNA sample with a special kind
of enzyme. This enzyme, a restriction endonuclease, cuts DNA at a
specific sequence pattern know as a restriction endonuclease
recognition site. The presence or absence of certain recognition sites
in a DNA sample generates variable lengths of DNA fragments, which
are separated using gel electrophoresis. They are then hybridized with
DNA probes that bind to a complementary DNA sequence in the
sample.
RFLP is one of the original applications of DNA analysis to forensic
investigation. With the development of newer, more efficient DNA-
analysis techniques, RFLP is not used as much as it once was
because it requires relatively large amounts of DNA. In addition,
samples degraded by environmental factors, such as dirt or mold, do
not work well with RFLP.
PCR Analysis
PCR (polymerase chain reaction) is used to make millions of exact
copies of DNA from a biological sample. DNA amplification with PCR
allows DNA analysis on biological samples as small as a few skin cells.
With RFLP, DNA samples would have to be about the size of a quarter.
The ability of PCR to amplify such tiny quantities of DNA enables even
highly degraded samples to be analyzed. Great care, however, must
be taken to prevent contamination with other biological materials
during the identifying, collecting, and preserving of a sample.
STR Analysis
Short tandem repeat (STR) technology is used to evaluate specific
regions (loci) within nuclear DNA. Variability in STR regions can be
used to distinguish one DNA profile from another. The Federal Bureau
of Investigation (FBI) uses a standard set of 13 specific STR regions
for CODIS. CODIS is a software program that operates local, state,
and national databases of DNA profiles from convicted offenders,
unsolved crime scene evidence, and missing persons. The odds that
two individuals will have the same 13-loci DNA profile is about one in
one billion.
Mitochondrial DNA Analysis
Mitochondrial DNA analysis (mtDNA) can be used to examine the DNA
from samples that cannot be analyzed by RFLP or STR. Nuclear DNA
must be extracted from samples for use in RFLP, PCR, and STR;
however, mtDNA analysis uses DNA extracted from another cellular
organelle called a mitochondrion. While older biological samples that
lack nucleated cellular material, such as hair, bones, and teeth, cannot
be analyzed with STR and RFLP, they can be analyzed with mtDNA. In
the investigation of cases that have gone unsolved for many years,
mtDNA is extremely valuable.
All mothers have the same mitochondrial DNA as their daughters. This
is because the mitochondria of each new embryo comes from the
mother's egg cell. The father's sperm contributes only nuclear DNA.
Comparing the mtDNA profile of unidentified remains with the profile of
a potential maternal relative can be an important technique in missing
person investigations.
Y-Chromosome Analysis
The Y chromosome is passed directly from father to son, so the
analysis of genetic markers on the Y chromosome is especially useful
for tracing relationships among males or for analyzing biological
evidence involving multiple male contributors.
The answer to this question is based on information from Using DNA to
Solve Cold Cases - A special report from the National Institute of
Justice (July 2002).
Some Interesting Uses of DNA Forensic Identification
Son of Louis XVI and Marie Antionette
PARIS, Apr 19, 2000 (Reuters) -- Scientists cracked one of the great
mysteries of European history by using DNA tests to prove that the son
of executed French King Louis XVI and Marie-Antoinette died in prison
as a child. Royalists have argued for 205 years over whether Louis-
Charles de France perished in 1795 in a grim Paris prison or managed
to escape the clutches of the French Revolution. In December 1999,
the presumed heart of the child king was removed from its resting
place to enable scientists to compare its DNA make-up with samples
from living and dead members of the royal family -- including a lock of
his mother Marie-Antoinette's hair.
Super Bowl XXXIV footballs and 2000 Summer Olympic souvenirs
The NFL used DNA technology to tag all of the Super Bowl XXXIV balls,
ensuring their authenticity for years to come and helping to combat the
growing epidemic of sports memorabilia fraud. The footballs were
marked with an invisible, yet permanent, strand of synthetic DNA. The
DNA strand is unique and is verifiable any time in the future using a
specially calibrated laser.
A section of human genetic code taken from several unnamed
Australian athletes was added to ink used to mark all official goods —
everything from caps to socks — from the 2000 Summer Olympic
Games. The technology is used as a way to mark artwork or one-of-a-
kind sports souvenirs.
Snowball the Cat
A woman was murdered in Prince Edward Island, Canada. Her
estranged husband was implicated because a snowy white cat hair was
found in a jacket near the scene of the crime, and DNA fragments from
the hair matched DNA fragments from Snowball, the cat belonging to
the husband's parents. M. Menotti-Raymond et al., "Pet cat hair
implicates murder suspect," Nature, 386: 774, 1997.
Angiosperm Witness for the Prosecution
The first case in which a murderer was convicted on DNA evidence
obtained from a plant was described in the PBS TV series, "Scientific
American Frontiers." A young woman was murdered in Phoenix,
Arizona, and a pager found at the scene of the crime led the police to
a prime suspect. He admitted picking up the victim, but claimed she
had robbed him of his wallet and pager. The forensic squad examined
the suspect's pickup truck and collected pods later identified as the
fruits of the palo verde tree (Cercidium spp.). One detective went back
to the murder scene and found several Palo Verde trees, one of which
showed damage that could have been caused by a vehicle. The
detective's superior officer innocently suggested the possibility of
linking the fruits and the tree by using DNA comparison, not realizing
that this had never been done before. Several researchers were
contacted before a geneticist at the University of Arizona in Tucson
agreed to take on the case. Of course, it was crucial to establish
evidence that would stand up in court on whether individual plants
(especially Palo Verde trees) have unique patterns of DNA. A
preliminary study on samples from different trees at the murder scene
and elsewhere quickly established that each Palo Verde tree is unique
in its DNA pattern. It was then a simple matter to link the pods from the
suspect's truck to the damaged tree at the murder scene and obtain a
conviction. [WNED-TV (PBS - Buffalo, N.Y.)]
DNA Forensics Databases
National DNA Databank: CODIS
CODIS: Combined DNA Index System
The COmbined DNA Index System, CODIS, blends computer and DNA
technologies into a tool for fighting violent crime. The current version
of CODIS uses two indexes to generate investigative leads in crimes
where biological evidence is recovered from the crime scene. The
Convicted Offender index contains DNA profiles of individuals
convicted of felony sex offenses (and other violent crimes). The
Forensic index contains DNA profiles developed from crime scene
evidence. All DNA profiles stored in CODIS are generated using STR
(short tandem repeat) analysis.
CODIS utilizes computer software to automatically search its two
indexes for matching DNA profiles. Law enforcement agencies at
federal, state, and local levels take DNA from biological evidence (e.g.,
blood and saliva) gathered in crimes that have no suspect and
compare it to the DNA in the profiles stored in the CODIS systems. If a
match is made between a sample and a stored profile, CODIS can
identify the perpetrator.
This technology is authorized by the DNA Identification Act of 1994. All
50 states have laws requiring that DNA profiles of certain offenders be
sent to CODIS. As of January 2003, the database contained more than
a million DNA profiles in its Convicted Offender Index and about 48,000
DNA profiles collected from crime scenes but which have not been
connected to a particular offender.
As more offender DNA samples are collected and law enforcement
becomes better trained and equipped to collect DNA samples at crime
scenes, the backlog of samples awaiting testing throughout the
criminal justice system has increased dramatically. In March 2003
President Bush proposed $1 billion in funding over 5 years to reduce
the DNA testing backlog, build crime lab capacity, stimulate research
and development, support training, protect the innocent, and identify
missing persons. For more information, seethe U.S. Department of
Justice's Advancing Justice Through DNA Technology.
Ethical, Legal, and Social Concerns about DNA
Databanking
The primary concern is privacy. DNA profiles are different from
fingerprints, which are useful only for identification. DNA can provide
insights into many intimate aspects of a person and their families
including susceptibility to particular diseases, legitimacy of birth, and
perhaps predispositions to certain behaviors and sexual orientation.
This increases the potential for genetic discrimination by government,
insurers, employers, schools, banks, and others.
Collected samples are stored, and many state laws do not require the
destruction of a DNA record or sample after a conviction has been
overturned. So there is a chance that a person's entire genome may
be available --criminal or otherwise. Although the DNA used is
considered "junk DNA" (STRs-single tandem repeated DNA bases), in
the future this information may be found to reveal personal information
such as susceptibilities to disease and certain behaviors.
Who is chosen for sampling is also a concern. In the United Kingdom,
for example, all suspects can be forced to provide a DNA sample.
Likewise, all arrestees --regardless of the degree of the charge and
the possibility that they may not be convicted--can be compelled to
comply. This empowers police officers, rather than judges and juries,
to provide the state with intimate evidence that could lead to
"investigative arrests." In the U.S., arresting people on less than
probable cause just to obtain DNA evidence raises the question of
Fourth Amendment violations against unreasonable search and
seizure.
Practicality also is a concern. An enormous backlog of over half a
million DNA samples waits to be entered into the CODIS system. The
statute of limitations has expired in many cases where the evidence
would have been useful for conviction .
Potential Benefits of DNA Databanking Arrestees
(According to Howard Safir, NYC Police Commissioner, 1999)
-Most major crimes involve people who also have committed minor
offenses.
-Innocent people currently are incarcerated for crimes they did not
commit; if samples had been taken at the time of arrest, these
individuals would have been excluded early in the investigative
process.
-Moving the point of testing from conviction to arrest would result in
savings in investigation, prosecution, and incarceration.
-Investigators would be able to compare other cases against the
arrested person's DNA profile, just as with fingerprints.
This new edition of a
bestseller emphasizes the
advantages and limitations
of various DNA techniques
used in the analysis of
forensic evidence. It covers
the shift to Short Tandem
Repeat (STR) technology,
and updates methods and
legal issues affected by this
shift. The authors discuss
forensic DNA issues from
both a scientific and legal
perspective, and present
the material in a manner
understandable by
professionals in the legal
system, forensic science,
and law enforcement.
bestseller emphasizes the
advantages and limitations
of various DNA techniques
used in the analysis of
forensic evidence. It covers
the shift to Short Tandem
Repeat (STR) technology,
and updates methods and
legal issues affected by this
shift. The authors discuss
forensic DNA issues from
both a scientific and legal
perspective, and present
the material in a manner
understandable by
professionals in the legal
system, forensic science,
and law enforcement.
Assessing Weight-of-
Evidence for DNA Profiles is
an excellent introductory
text to the use of statistical
analysis for assessing DNA
evidence. It offers practical
guidance to forensic
scientists with little
dependence on
mathematical ability as the
book includes background
information on statistics –
including likelihood ratios –
population genetics, and
courtroom issues.
The author, who is highly
experienced in this field,
has illustrated the book
throughout with his own
experiences as well as
providing a theoretical
underpinning to the
subject. It is an ideal choice
for forensic scientists and
lawyers, as well as
statisticians and population
geneticists with an interest
in forensic science and DNA
Evidence for DNA Profiles is
an excellent introductory
text to the use of statistical
analysis for assessing DNA
evidence. It offers practical
guidance to forensic
scientists with little
dependence on
mathematical ability as the
book includes background
information on statistics –
including likelihood ratios –
population genetics, and
courtroom issues.
The author, who is highly
experienced in this field,
has illustrated the book
throughout with his own
experiences as well as
providing a theoretical
underpinning to the
subject. It is an ideal choice
for forensic scientists and
lawyers, as well as
statisticians and population
geneticists with an interest
in forensic science and DNA
Honest but mistaken
eyewitnessesare the
leading cause of wrongful
convictions in the United
States. As the innocent go
to prison their lives are
shattered; as the criminal
goes free, the public
remains vulnerable. With a
vivid cast of brilliant
scientists, street-wise cops,
and former prosecutors--all
haunted by the legacy of
wrongful convictions, some
directly involved with
one--Doyle sheds light on
the intersection of personal
ambition, legal and political
principles, and scientific
inquiry. He highlights real
possibilities for improved
identification, their
challenges to the legal
tradition, and persuasively
argues that the promises of
improved justice must be
realized before another
wrongful conviction lets the
guilty go free. This is an
important look at a pressing
issue in the news with every
exoneration.
eyewitnessesare the
leading cause of wrongful
convictions in the United
States. As the innocent go
to prison their lives are
shattered; as the criminal
goes free, the public
remains vulnerable. With a
vivid cast of brilliant
scientists, street-wise cops,
and former prosecutors--all
haunted by the legacy of
wrongful convictions, some
directly involved with
one--Doyle sheds light on
the intersection of personal
ambition, legal and political
principles, and scientific
inquiry. He highlights real
possibilities for improved
identification, their
challenges to the legal
tradition, and persuasively
argues that the promises of
improved justice must be
realized before another
wrongful conviction lets the
guilty go free. This is an
important look at a pressing
issue in the news with every
exoneration.
There's no question that we're living in
a time like no other. The speed with
which scientific and technological
advancements are occurring is mind
boggling. The implications of DNA
evidence processes and techniques on
law enforcement cannot be overstated.
But...before you start thinking that
DNA, particularly in the area of suspect
identification, is going to be some kind
of magic bullet, take a step back and
focus in on the real world. While the
science itself is indeed impressive,
you've got to factor in people when you
apply forensic science, or any kind of
high technology, to law enforcement.
There's some fantastic computer
information technology available to
police departments that are still
struggling to utilize even a fraction of its
potential. Sadly, they don't do a great
job of even utilizing that fraction. When
it comes to DNA technology, you've got
the same people determining the
acquisition, use and maintenance of
DNA technology.
This may not be immediately obvious to
you, but the biggest, and most
important, benefit of DNA identification
a time like no other. The speed with
which scientific and technological
advancements are occurring is mind
boggling. The implications of DNA
evidence processes and techniques on
law enforcement cannot be overstated.
But...before you start thinking that
DNA, particularly in the area of suspect
identification, is going to be some kind
of magic bullet, take a step back and
focus in on the real world. While the
science itself is indeed impressive,
you've got to factor in people when you
apply forensic science, or any kind of
high technology, to law enforcement.
There's some fantastic computer
information technology available to
police departments that are still
struggling to utilize even a fraction of its
potential. Sadly, they don't do a great
job of even utilizing that fraction. When
it comes to DNA technology, you've got
the same people determining the
acquisition, use and maintenance of
DNA technology.
This may not be immediately obvious to
you, but the biggest, and most
important, benefit of DNA identification
Every police academy in the nation should include in its curriculum an
in depth examination of the Duke Lacrosse Rape Case.
The three young men named as suspects in this case were fortunate
enough to come from families who could afford to hire "real" attorneys
who were willing to expose the corruption of one in their own profession.
Ironically, the only reason DA Nifong arbitrarily targeted the three men
was because they came from what many would consider a position of
social privilege. The proof of this was in the fact that these hapless
"suspects" had none of the usual civil rights activists and organizations
coming to their support.
It's a scary thought to think about what could have happened if this case
had ever gone to trial. It's not a leap to believe that this prosecutor
would have attempted to permanently conceal the true DNA results as
inconclusive. Fortunately, that did not happen, and the DNA saved
them.
While DNA identification can be applied to many different types of
crimes, you'll find that rape and sexual assault investigations will
routinely rely on the benefits of DNA identification for obvious reasons.
However, keep in mind that while the DNA identification is a very
important part of the investigation, it is only one part, and it can be
problematic.
In the example of the Duke Rape Case, it's obvious that the alleged
victim had experienced recent vaginal intercourse with four different
men. DNA testing can establish that intercourse occurred, but it cannot
determine if the intercourse was the result of rape...that's what a police
investigation must determine through a comprehensive and competent
investigation. In the Duke Rape Case, comprehensive and competent
were never parts of the equation.
When you begin your police career, you should soon observe that
evidence comes in many forms. In most instances, forensic evidence,
e.g. DNA; firearms, fingerprints, etc., will only confirm or support
conclusions already derived from other aspects of your investigation.
When the forensic evidence refutes a conclusion, it gives you the
opportunity to change or expand the direction of your investigation. At
some point, when all the parts fit together, you've solved your crime,
and you'll be prosecuting the right person(s).
In 2006 Michael Nifong, the Durham, NC, District Attorney,
knowingly and cynically manipulated sex, race and social privilege
for his own political gain at the expense of three totally innocent
young men. The national media's attention was initially drawn to
the case, because three white Duke University Lacrosse players
were accused of violently raping and sodomizing a young African
American exotic dancer at an off campus party.
After a quick Grand Jury Indictment was obtained, where
interestingly no transcription of the proceeding was recorded, the
District Attorney's case almost immediately began to fall apart. To
the media's credit, it stuck with the story. Of course, it was too
good to pass up. About three months into the drama, the District
Attorney's totally manipulated photo identification of the suspects
was revealed. While the judges in Durham sat on their hands, calls
went out to the State Attorney General to enter the prosecution
which the District Attorney was determined to take to trial.
For a very long time the TV prosecutor pundits extolled the virtues
of the criminal justice system insisting that the prosecutor must
have something everyone was missing, and everything would be
sorted out at trial. It was obvious none of them had ever faced a
wrongful prosecution where sex, race, rape and politics would be
merged into one big activist agenda sitting like the 800 pound
gorilla in that court room.
Early on everybody talked about DNA. I don't think anyone will
ever know exactly when the District Attorney knew the DNA
results would exonerate the suspects. When the DA's attempts to
conceal the results from defense lawyers were revealed, he simply
dropped the rape charges leaving charges of kidnapping and other
sexual assaults intact. He knew that DNA from four different men
were inside the alleged victim; however, the DNA did not match the
suspects or any of the other 43 young men at the party.
Finally, after nine months of this absurd non-investigation and
prosecution, the State Attorney General set the best and brightest
from his office to the task of saving the North Carolina Criminal
Justice System. After another three months, the Attorney General
announced that the suspects were "innocent." The pundits fell all
over themselves at the pronouncement, because a declaration of
innocence from a prosecutor was unprecedented. But...what choice
did he have? The Attorney General was already about six months
behind the curve, before he acted. DA Nifong's absurd and
outrageous prosecutorial misconduct had made the "innocent"
pronouncement, versus the standard "insufficient evidence" tag, a
matter of politics rather than justice. It worked well...the use the
innocent label prevented continuing criticism, and the Attorney
General received praise despite his office's long period of inaction.
The North Carolina Bar Association even saw the wisdom in
dumping one of their own, and they acted quickly to disbar their
rogue brother. Of course, neither the Attorney General, nor the
Bar Association, saw any need in identifying and disciplining any of
DA Nifong's deputies who aided their boss either overtly or by
negligently ignoring his misconduct. To be sure, the Durham
Police Department was part of the problem, but, in this case, you
couldn't have gotten to any bad cops without first going through
some more bad lawyers.
knowingly and cynically manipulated sex, race and social privilege
for his own political gain at the expense of three totally innocent
young men. The national media's attention was initially drawn to
the case, because three white Duke University Lacrosse players
were accused of violently raping and sodomizing a young African
American exotic dancer at an off campus party.
After a quick Grand Jury Indictment was obtained, where
interestingly no transcription of the proceeding was recorded, the
District Attorney's case almost immediately began to fall apart. To
the media's credit, it stuck with the story. Of course, it was too
good to pass up. About three months into the drama, the District
Attorney's totally manipulated photo identification of the suspects
was revealed. While the judges in Durham sat on their hands, calls
went out to the State Attorney General to enter the prosecution
which the District Attorney was determined to take to trial.
For a very long time the TV prosecutor pundits extolled the virtues
of the criminal justice system insisting that the prosecutor must
have something everyone was missing, and everything would be
sorted out at trial. It was obvious none of them had ever faced a
wrongful prosecution where sex, race, rape and politics would be
merged into one big activist agenda sitting like the 800 pound
gorilla in that court room.
Early on everybody talked about DNA. I don't think anyone will
ever know exactly when the District Attorney knew the DNA
results would exonerate the suspects. When the DA's attempts to
conceal the results from defense lawyers were revealed, he simply
dropped the rape charges leaving charges of kidnapping and other
sexual assaults intact. He knew that DNA from four different men
were inside the alleged victim; however, the DNA did not match the
suspects or any of the other 43 young men at the party.
Finally, after nine months of this absurd non-investigation and
prosecution, the State Attorney General set the best and brightest
from his office to the task of saving the North Carolina Criminal
Justice System. After another three months, the Attorney General
announced that the suspects were "innocent." The pundits fell all
over themselves at the pronouncement, because a declaration of
innocence from a prosecutor was unprecedented. But...what choice
did he have? The Attorney General was already about six months
behind the curve, before he acted. DA Nifong's absurd and
outrageous prosecutorial misconduct had made the "innocent"
pronouncement, versus the standard "insufficient evidence" tag, a
matter of politics rather than justice. It worked well...the use the
innocent label prevented continuing criticism, and the Attorney
General received praise despite his office's long period of inaction.
The North Carolina Bar Association even saw the wisdom in
dumping one of their own, and they acted quickly to disbar their
rogue brother. Of course, neither the Attorney General, nor the
Bar Association, saw any need in identifying and disciplining any of
DA Nifong's deputies who aided their boss either overtly or by
negligently ignoring his misconduct. To be sure, the Durham
Police Department was part of the problem, but, in this case, you
couldn't have gotten to any bad cops without first going through
some more bad lawyers.
| ...DNA saved them |
is its ability to
protect innocent
people from being
wrongly convicted
and imprisoned for
crimes they did not
commit. As long as
you maintain high
ethical standards
throughout your
career, you won't
even need DNA to
tell you when you
don't have a case.
Unfortunately, there
are some police
protect innocent
people from being
wrongly convicted
and imprisoned for
crimes they did not
commit. As long as
you maintain high
ethical standards
throughout your
career, you won't
even need DNA to
tell you when you
don't have a case.
Unfortunately, there
are some police
officers and prosecutors who have infinite faith in their ability to
interrupt evidence any way they like...if some facts don't fit, ignore
them...if some facts need a little creative manipulation, that's okay too.
interrupt evidence any way they like...if some facts don't fit, ignore
them...if some facts need a little creative manipulation, that's okay too.