U.S. Department of Justice

Office of Justice Programs

Office for Victims of Crime

Understanding DNA

Evidence: A Guide for

Victim Service Providers

by Kathryn M.Turman

APRIL 2001

D NA evidence is playing a larger

role than ever before in criminal

cases throughout the country, both

to convict the guilty and exonerate the

wrongly accused. Biological samples that

were impossible to test for DNA 10 years

ago may yield critical evidence if tested

today. Because DNA evidence is a powerful tool in the search for truth, it is important that victim service providers

understand the potential significance of

DNA evidence in their clients’ cases.

What Is DNA?

D NA, or deoxyribonucleic acid, is

the fundamental building block 

for an individual’s entire genetic

makeup—our hereditary blueprint passed

on to us by our parents. It is a component

of virtually every cell in the human body.

A person’s DNA is the same in each cell

and it does not change throughout a person’s lifetime. For example, the DNA in

a person’s blood is the same as the DNA

found in that person’s saliva. DNA also is

found in skin tissue, sweat, bone, the root

and shaft of hair, earwax, mucus, urine,

semen, and vaginal or rectal cells. Parts

of the DNA determine our physical characteristics, such as eye and hair color,

height, and bone structure, but the DNA

collected from the crime scene is for evidentiary purposes only and not to determine an assailant’s physical characteristics.

The Value of DNA

Evidence

D NA is a powerful investigative tool

because, with the exception of

identical twins, no two people

have the same DNA. In other words, the

sequence or order of the DNA building

blocks is different in particular regions of

the cell, making each person’s DNA

unique. Therefore, DNA evidence collected from a crime scene can link a suspect to a crime or eliminate one from

suspicion in the same way that fingerprints are used. DNA also can identify a

About This

Bulletin

Stories about the use of DNA evidence to convict offenders or exonerate defendants in criminal cases have

appeared in the media with increasing

frequency over the last few years.

Criminal justice professionals and the

public realize that forensic DNA technology is revolutionizing the way law

enforcement officers investigate violent

crimes, including crime scene investigation, counseling rape victims to not

wash away critical evidence, accurate

conviction of offenders, and connecting

offenders to other brutal crimes.This

bulletin seeks to strengthen crime victims’ confidence in the judicial process

by showing how DNA technology can

empower the search for truth.

The importance of DNA evidence has

grown considerably in recent years as

improved technology renders more accurate results and DNA evidence is

used more frequently to convict or exonerate defendants.As a result of its

awesome ability to convict a perpetrator or exonerate a convicted offender,

particularly in sexual assault and homicide cases, DNA evidence has become

a powerful crimefighting tool.This is

precisely why victim service providers

need to know the significance of DNA

evidence in victims’ cases.They also

should understand how the identification,

Continued on page 2
victim through the DNA of relatives if a

victim’s body cannot be found. For example, if technicians have a biological sample from the victim, such as a bloodstain

left at a crime scene, the DNA taken

from that evidence can be compared with

DNA from the victim’s biological relatives to determine if the bloodstain belongs to the victim. When a DNA profile

developed from evidence at one crime

scene is compared with a DNA profile

developed from evidence found at another crime scene, they can be linked to

each other or to the same perpetrator,

whether the crime was committed locally

or in another state.

DNA evidence in the form of saliva,

blood, skin tissue, hair, and semen are

often recovered from crime scenes and

can be crucial to the investigation of sexual assaults and other violent crimes. For

example, during a sexual assault, biological evidence such as hair, skin tissue,

semen, blood, or saliva can be left on the

victim’s body or at the crime scene. In addition, hair and fiber from clothing, carpet, bedding, or furniture could be

transferred to the victim’s body during an

assault. This evidence is helpful in proving that there was physical contact between an assailant and a victim. DNA

properly collected from the victim, crime

scene, or suspect can be compared with

known samples to place the suspect at the

scene of the crime. If there is no suspect,

however, a DNA profile of the crime

scene can be entered into the Federal

Bureau of Investigation’s (FBI) Combined

DNA Index System (CODIS), which allows agencies to match DNA profiles

with other profiles entered into local,

state, and national databases to identify

a suspect or link serial crimes.

As with fingerprints, the effective use of

DNA as evidence may require the collection and analysis of elimination samples

to determine whether biological evidence

came from a suspect or someone else.

When investigating sexual assault or rape

cases, it may be necessary to obtain an

elimination sample, such as a blood or

saliva sample, from the victim’s relatives

or consensual sex partner to account for

all of the DNA found on the victim or at

the crime scene.

Evidence Collection

and Preservation

A

lthough this bulletin is not intended as an instructional manual for

DNA evidence collection, every

victim service provider should be aware

of important issues involved in the identification, collection, transportation, and

storage of DNA evidence. These issues

are as important for the victim service

provider as they are for the crime scene

technician, nurse examiner, or other

medical personnel. If DNA evidence is

not initially identified, it may not be

collected, and if DNA evidence is not

properly collected, it may become contaminated or degraded. If properly preserved, however, DNA from body fluid

stains or bones can be tested after many

years in older cases in which questions of

identity remain unresolved or disputed.

In many cases, these substances can be

analyzed to reliably link criminals to

crimes or clear them as suspects.

It is crucial that victims of sexual assault

understand why they should not change

clothes, shower, or wash any part of their

body after the assault. Semen may be

found on clothing, bedding, or in the victim’s vaginal, rectal, or oral regions.

Saliva, which contains valuable DNA,

can be found on an area where the victim

was licked or bitten. In addition, if the

victim scratched the assailant, skin tissue

that contains the assailant’s DNA can

be collected from beneath the victim’s

fingernails. 

Although evidence technicians may be

able to collect fingerprints and other

valuable forensic evidence from the crime

scene, evidence that may be inside or on

a victim’s body should only be collected

by a physician or sexual assault nurse examiner. A medical examination ideally

should be conducted within hours of the

assault to treat injuries, test for sexually

transmitted diseases, and collect forensic

evidence. The doctor or nurse examiner

will use a special kit that contains sterile

cotton swabs to collect fluids from the

vaginal cavity, mouth, or other parts of

the victim’s body that may have come in

contact with the assailant. Fingernail

scrapings and hair also may be collected

as forensic evidence at this time. The victim’s clothes, especially undergarments,

that were worn during and/or after the 

OVC Bulletin

2

About This Bulletin

Continued from page 1

collection, and preservation of DNA at

the crime scene is critical in obtaining

accurate test results.

Victims need to be provided with a

simple but thorough explanation of

how DNA testing may be used in their

case, the process and procedures used,

and the potential outcomes of the test

results. It is important that victim service providers relay this information to

victims early in the investigative process

to help victims understand how DNA is

used in investigating crimes and how it

can improve the chances of apprehending and convicting an offender.

DNA evidence is a useful and neutral

tool in the search for justice.Whether

it helps convict or absolve individuals,

DNA evidence will play an increasingly

important role in solving crimes in the

future.The result will be better justice

for victims and safer communities.
assault should be collected for evidentiary

purposes. In addition, the examiner will

take a control standard from the victim in

the form of blood or saliva and may collect a sample of the victim’s head and

pubic hair. Given the sensitive nature of

DNA evidence, victim service providers

should contact their crime laboratory personnel or evidence technicians when collection questions arise.

Contamination Issues

Because extremely small amounts of

DNA can be used as evidence,

greater attention to contamination

issues is necessary when identifying, collecting, and preserving DNA evidence.

DNA evidence can become contaminated when DNA from another source gets

mixed with DNA relevant to the case.

This can happen if someone sneezes or

coughs over the evidence, or if the person

collecting the evidence touches his/her

mouth, nose, hair, or any other part of

his/her body, and then touches the area

that may contain the DNA to be tested.

In addition, environmental factors, such

as heat and humidity, can accelerate the

degradation of DNA. Degradation refers

to the breaking down of DNA into smaller fragments by chemical or physical

means. For example, wet or moist evidence that is packaged in plastic will provide a growth environment for bacteria,

which can destroy DNA evidence.

Biological evidence should always be

thoroughly air-dried, packaged in paper,

and properly labeled, ensuring that the

chain of custody—a process used to document the chronological history of the 

evidence—is maintained. DNA evidence

that is properly identified, collected, and

preserved can be stored for years without

risk of extensive degradation, even at

room temperature.

Forensic DNA Testing

A

nalyzing DNA evidence in a criminal case can take weeks or months

to complete and can be expensive,

especially if multiple pieces of evidence

are submitted. During a criminal investigation, the police department or the prosecutor’s office often pays for the analysis.

In criminal DNA cases, laboratory personnel should work with the police department and prosecutor to decide which

evidence may be most probative to the

case. Once a decision is made about what

evidence should be tested, the laboratory

will extract and analyze the DNA.

The laboratory analysis of DNA involves

the examination of a DNA strand at 13

specific locations (loci). The DNA profile

from biological evidence collected from a

crime scene can be compared with a profile from a known source (for example, a

semen stain from a crime scene could be

compared with a blood or saliva sample

from a suspect). The DNA profiles from

the biological evidence are compared

with the profile from a suspect at the loci

tested. If the profiles are the same, a statistic is generated which reflects how

often one would expect to find this particular DNA profile in the general population. This helps in the analysis to

determine whether the evidence likely

came from the suspect or not. In addition,

this process can seek the source of DNA

evidence found at a crime scene by comparing the profile to convicted offenders

in the CODIS database in situations

where investigators may not yet have a

suspect.

DNA Testing Methods

T

hree methods are currently used to

analyze DNA evidence. While these

methods are very reliable, sometimes

results cannot be obtained or are inconclusive if the quantity of the evidence is

insufficient to analyze or if the evidence

has been contaminated or improperly preserved. The technology used in analyzing

DNA evidence is increasing in sophistication and in its ability to distinguish 

individuals, so it may be possible to test

evidence in the future in ways that are

not possible today.

The most common form of DNA analysis is called polymerase chain reaction

(PCR). The development of PCR testing

has greatly advanced the field of forensic

DNA testing by increasing the success

rate of the analysis of old, degraded, or

very small biological evidentiary samples. PCR testing has allowed investigators to analyze evidence samples that

previously could not be tested because

the quality or the amount of starting material was insufficient for previous DNA

analysis techniques.

The PCR process works by taking very

small amounts of DNA from biological

evidence and making millions of copies of

it. This process, often referred to as PCR

amplification, creates enough DNA to

allow a laboratory analyst to generate a

DNA profile. The process also allows laboratory technicians to analyze degraded

biological material. A group of 13 different locations is used for the analysis of

evidentiary samples and to generate DNA

profiles from convicted offenders for the

CODIS database.

Because of the capability of PCR testing

to amplify very small quantities of DNA,

3

UNDERSTANDING DNA EVIDENCE: A GUIDE FOR VICTIM SERVICE PROVIDERS
extreme care must be exercised to prevent contamination when identifying,

collecting, and preserving biological evidence. For this reason, investigators and

laboratory personnel should always wear

disposable gloves, use clean instruments,

and avoid touching other objects when

handling the evidence.

The other two methods used to analyze

DNA evidence are restriction fragment

length polymorphism (RFLP) testing and

PCR testing on DNA from the mitochondria of the cell. RFLP testing usually

requires a sample that has 100,000 or

more cells (such as a dime-sized bloodstain) and contains DNA that is not degraded or broken into smaller fragments.

RFLP has been widely used since the late

1980s and is able to exclude wrongly accused individuals. PCR testing on DNA

from the mitochondria of the cell is conducted on samples that are unsuitable for

RFLP or PCR nuclear DNA testing (such

as dried bones or teeth, hair shafts, or

samples that contain very little or highly

degraded nuclear DNA). Mitochondrial

DNA testing is available only in a limited

number of laboratories primarily because

of the time it takes to perform the tests.

Interpreting Results of

DNA Analysis

T

hree types of results can occur in

DNA testing: inclusion, exclusion,

and inconclusive results. It is important that victim service providers, investigators, and prosecutors understand the

meaning of these terms and be able to explain their implications. While conclusive results are very reliable, DNA

findings can sometimes yield results that

are difficult to interpret.

Inclusion

When the DNA profile of a known individual (a victim or suspect) matches

the DNA profile from the crime scene 

evidence, the individual is “included” 

as a potential source of that evidence.

However, the strength of this inclusion

depends, in part, on the number of DNA

locations examined (up to 13 locations

can be examined) and the statistic reflecting how often the particular profile

would be found in the general population.

A DNA profile shown to occur rarely in

the population (for example, 1 time in 5

million people) would more strongly suggest that the individual is the source of

the biological evidence than would a

more common DNA profile (for example,

1 time in 5,000 people). Increasing the

number of DNA locations tested typically

results in more powerful statistics. For this

reason, several DNA locations are tested

whenever possible.

In some cases, a DNA inclusion may provide information that is of limited value

to the investigative process. For example,

results from samples taken from the victim may be consistent with the DNA of

the victim, such as vaginal evidence in

sexual assault cases. In addition, if the

suspect wore a condom during the assault,

was aspermatic due to a vasectomy, or did

not ejaculate after the assault, additional

DNA profiles may not be obtained from

the evidence. The results do not mean

the suspect was not present and did not

commit the crime—only that the substance tested did not come from the suspect. Additionally, inclusion does not

necessarily mean a suspect is guilty.

Exclusion

When the DNA profile from an individual (a victim or suspect) does not

match the DNA profile generated from

the crime scene evidence, the referenced

individual is “excluded” as the donor of

the evidence. In some cases, it may be

necessary to perform additional testing to

establish the source of the DNA profile

in the evidence. For example, a blood

sample may be requested from the husband of a sexual assault victim to determine whether the DNA profile obtained

from the vaginal swab is the result of a

prior consensual act and not the assault.

Exclusion does not necessarily mean a

suspect is innocent. 

Inconclusive Results

Inconclusive results indicate that

DNA testing did not produce information

that would allow an individual to be either included or excluded as the source of

the biological evidence. Inconclusive results can occur for many reasons. For example, even with sensitive PCR testing,

the quality or quantity of DNA obtained

from the biological evidence may be insufficient to produce definitive DNA typing results. Inconclusive results also can

occur if the evidentiary sample contains a

mixture of DNA from several individuals

(for example, a sample taken from a victim of a gang rape). Even if the suspect’s

DNA profile is found in the biological

evidence, the presence of DNA from

other sources may prohibit the establishment of an inclusive or exclusive result. If

there is more than one perpetrator or if in

a sexual assault case the victim recently

had consensual intercourse in which

semen also may have been deposited in

the victim’s vaginal region, the results

could contain profiles from more than

one person. When this happens, it

is often not possible to determine which

specific types came from which donor.

The suspect cannot be excluded as a possible donor of the DNA found in the evidence sample, but a more conclusive

result may not be possible. These cases

must be reported as inconclusive. As with 

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all DNA results, inconclusive findings

should be interpreted in the context of

the other evidence in a case.

DNA Evidence:

Closed Cases and

Unsolved Cases

A

lthough DNA technology can be

used in criminal cases to place a

suspect at the scene of a crime, it

also can be used to solve cases where no

suspect previously existed. In addition, it

can be used to reevaluate prior convictions to determine innocence. Using new

technology to analyze DNA evidence in

old cases can provide answers to questions of guilt or innocence and remove

lingering doubts. Many postconviction

DNA cases have released wrongly convicted individuals based on evidence that

was unsuitable for early DNA testing.

The development of advanced technology, such as PCR testing, makes it possible

to obtain conclusive results in cases in

which previous testing might have been

inconclusive. It is important to realize

that while the testing or retesting may exonerate the individual, exclusionary results may not prove actual innocence.

Prosecutors, defense counsel, the court,

and law enforcement should concur on

the need for testing on a case-by-case

basis.

Using CODIS To

Solve Crimes

T

he real investigative power of DNA

technology can be realized in its application to cases where a suspect

has not yet been identified. DNA technology and the FBI’s CODIS database

can help law enforcement identify perpetrators or link serial crimes. CODIS uses

two indices to generate investigative

leads in crimes that contain biological 

evidence—the forensic index contains

DNA profiles from biological evidence

left at crime scenes, and the offender

index contains DNA profiles of individuals convicted of violent crimes. Each state

has a DNA database law that defines

which convicted offenders must enter

their profiles into the database. Some

states have expanded their laws to require

that all felons enter their DNA profiles

into the state’s database. The CODIS

database enables local, state, and federal

forensic crime laboratories to work together to solve crimes between jurisdictions or across state lines. While CODIS

is operated on the state level, the FBI’s

national database (also known as the

National DNA Index System or NDIS)

may link profiles from the databases of

each of the 50 states to provide law enforcement with a national network to investigate violent crime. The CODIS

database will continue to have an impact

on the identification of serial rapists and

murderers who have committed crimes in

more than one jurisdiction. It is important to realize that although the power of

the CODIS database primarily is used in

identifying perpetrators of crime, it also

can affirm a suspect’s innocence.

Case Studies: The

Power of a DNA

Match

Nothing illustrates the power of

DNA evidence more effectively

than the case studies—or real-life

experiences—of those whose lives have

been changed by such evidence. Whereas

some case studies demonstrate DNA’s

ability to exonerate inmates wrongfully

convicted of crimes, others show the

powerful sense of closure and relief that

a DNA match can bring to victims of 

violent crime. The three very different

case studies presented below reflect the

power of a DNA match and reveal some

of the complexities involved in the criminal justice system. Given the pain suffered and the time irrevocably lost, these

individuals’ stories also indicate an urgent

need to improve the capabilities and response times of DNA databases and eliminate the growing backlog of rape kits.

A Lifetime Struggle: The

Courage of Kellie Greene

Kellie Greene’s life changed forever

late one January evening more than 7

years ago following a visit to the laundry

room in her apartment complex. As she

opened the door to her apartment, she

was brutally attacked by an intruder who

smashed a tea kettle over her head and

then raped her. At some point during the

vicious attack, which lasted 45 minutes,

Kellie’s rapist used dishwashing detergent.

It is unknown whether the rapist used it

as a lubricant, after ejaculation to cleanse

himself, or purposely to destroy crucial

DNA evidence that ultimately could convict him of the assault. In any case, forensic experts with the Florida Department

of Law Enforcement were able to retrieve

a sample of the rapist’s semen from the

sweater Kellie wore that night. It was this

key DNA evidence that, on February 28,

1997, linked David William Shaw to

Kellie’s attack on January 18, 1994. More

than a month would pass, however, before she was told of the DNA match in

April 1997.

The road to recovery for Kellie, and

countless other rape survivors, is paved

with anger, loss, rage, sadness, numbness,

confusion, shame, guilt, fear, despair, and

courage. The rape is a memory that never

disappears and one that marks a woman’s

life forever. The experience shapes

how she reacts to life’s challenges and 

UNDERSTANDING DNA EVIDENCE: A GUIDE FOR VICTIM SERVICE PROVIDERS
unexpected turns, how she gets through

each day, how she sleeps at night, how

she feels about her sexuality, how she

feels about her body, and how she feels

about men. “I think I always will struggle

with the sexuality. It’s never the same.

Something that should be natural becomes something that you have to work

at,” Kellie said.

After Kellie’s brutal attack and rape, she

did not hesitate to report it to the authorities. “There wasn’t any question. I was

beat up really badly,” she said. But once

at the hospital, Kellie had to wait 3 hours

in a hospital bed with her head wound

still bleeding because the hospital would

not treat her without first being seen by a

medical examiner. It took seven staples to

close the gash in her head.

At the time of her rape, Florida was not

processing nonsuspect cases because of

funding issues, and, as a result, DNA evidence in her case sat on a shelf for more

than 3 years before it was analyzed. If it

had not been for persistent law enforcement officers, particularly one detective,

Kellie’s rape kit might still be sitting on a

shelf. Because officers thought Kellie’s

rape was similar to rapes occurring in

Daytona Beach, less than 2 hours north

of Orlando where Kellie’s attack occurred,

her rape kit was dusted off and examined.

Once the results were entered into

Florida’s local DNA database, a hit was

made via the FBI’s CODIS system, allowing for an almost immediate match. Her

rapist’s DNA profile did not match the

profile of the rapist in Daytona Beach but

that of a man already serving a 25-year

sentence for beating and raping a woman

6 weeks before attacking Kellie.

While Kellie’s rapist remains behind bars

today, she continues to fight to keep him

there. Quirks in the criminal justice system, insensitivity toward the victim, and

human error allowed her case to slip

through the cracks more than once, resulting in a significantly reduced sentence

for the offender. Not until late April 2000

was Kellie informed of a plea agreement

stating that Shaw could serve concurrently a 22-year sentence for Kellie’s rape, a

15-year sentence for a robbery, a 5-year

sentence for obstructing justice, and the

25-year sentence for the first rape. A motion filed by the defense attorney to clarify the sentence never reached the state’s

attorney’s office. Finally, the judge signed

orders denying Kellie restitution and

denying her request that Shaw be treated

with chemical castration shots. As a 

result, Kellie’s rapist could be released

from jail as early as 2001. Had consecutive sentences been ordered for his brutal

crimes, he would not be released until

2041.

After her trial, Kellie drafted and introduced a bill in the Florida legislature that

would mandate consecutive sentences for

convicted sex offenders and murderers in

prison who are found guilty of subsequent

offenses. Sponsored by Representative

Randy Johnson (R), the legislation was

called the Sexual Predator Prosecution

Act of 2000. The bill passed Florida’s

House and Senate unanimously and was

signed into law in June 2000.

Kellie has been speaking out about her

rape and recovery for more than 6 years.

In October 1999, she formed a nonprofit

organization named SOAR—Speaking

Out About Rape, Inc. She travels across

the country giving rape awareness seminars about the healing process and the

importance of DNA evidence in solving

cases. SOAR gave her recovery a purpose.

“I was able to learn something from it and

to help others. So often people think of

the rape only and not the aftereffects,”

she pointed out. “DNA is really an amazing tool. You don’t know where you’re

going to get the DNA from but you can

get it from a lot of places.”

Note: If you would like to contact Kellie

Greene or find out more about SOAR, call

407–836–9692, fax 407–836–9690, or visit

SOAR’s Web site at www.soar99.org.

A First Step Toward Healing:

Crime Victim Debbie Smith’s

Story

Everything changed for rape victim

Debbie Smith when the man who had

raped her 6 years earlier was identified.

When processed through Virginia’s

DNA databank, the DNA sample of her

assailant collected years earlier had produced a match or “hit” with DNA of an

inmate in a Virginia prison. As reflected

by her compelling testimony before the

National Institute of Justice’s National

Commission on the Future of DNA

Evidence, that DNA match gave Debbie

final proof that her assailant would not

“come back” for her, as he had threatened. What is more important is that it

allowed her to begin healing.

Debbie’s ordeal began at about 1 p.m. on

May 3, 1989, at her home in Williamsburg, Virginia. She was cleaning house,

doing laundry, and baking a cake. A light

rain was falling, and her husband—a police lieutenant—was upstairs sleeping

after working the night shift and appearing in court that morning. After stepping

outside briefly, Debbie came back in and,

for some reason, left the door unlocked.

Within a few minutes, a masked stranger

entered Debbie’s house and nearly destroyed her life. The stranger dragged

Debbie to a wooded area. He blindfolded

her. He robbed her. And he raped her repeatedly, telling her, “Remember, I know

where you live and I will come back if

you tell anyone.”

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When allowed to return home, Debbie

told her husband about the attack but in

fear begged him not to call the police.

She just wanted to take a shower and

wash away the pain. Debbie’s husband,

however, convinced her to notify the 

police and visit a hospital where trained

medical personnel could examine her and

collect physical evidence that might

identify the rapist. If she showered, that

evidence would be lost. Debbie thanks

God every day for her husband’s advice.

Although she was “plucked and scraped

and swabbed” during her visit to the hospital, Debbie’s rape examination kit produced the crucial DNA evidence that

ultimately identified her attacker.

True peace of mind came for Debbie

Smith on July 26, 1995, when a forensic

scientist for the Commonwealth of

Virginia notified Debbie that a DNA

match had been made. Her assailant was

serving time in a Virginia prison for a separate offense. For the first time since the

rape, Debbie knew that her attacker

could not come after her. Debbie learned

later that her assailant had gone to jail

only months after raping her. Because of a

backlog in Virginia’s DNA database, she

waited 6 years to hear about it.

Proof of Innocence: Inmate

Ronald Cotton’s Story

Ronald Cotton’s story begins on a 

summer night in 1984 when two rapes

were committed in Burlington, North

Carolina. In each case, an assailant entered an apartment, cut the phone wires,

raped a woman at knifepoint, and stole

money and other items. Both victims

were taken to the hospital, where full

rape examination kits were completed.

The first victim, 22-year-old Jennifer

Thompson, described her attacker as a

tall African-American man in his early

20s. Police collected photographs of area

men meeting that description, including

22-year-old Ronald Cotton, a Burlington

resident employed at a restaurant near

Thompson’s apartment. Cotton had two

prior convictions: one for breaking and

entering, and another for assault with 

intent to rape. Thompson selected

Cotton from police photos as her rapist.

When Cotton visited the police station

to clear up the misunderstanding, he only

strengthened the case mounting against

him. He claimed that he had been with

friends on the night of the rapes, but

those friends did not corroborate his

alibi. At a physical lineup of suspects,

Thompson again selected Cotton. In

August 1984, police arrested Cotton and

took him into custody. In January 1985,

Cotton was convicted of Thompson’s

rape and sentenced to life in prison. That

verdict, however, was overturned, and a

new trial was ordered. Cotton was optimistic given a crucial discovery he had

made about one of his fellow inmates,

Bobby Poole—a tall African-American

young man from Burlington also convicted of rape who bore a strong resemblance

to the composite sketch used in Cotton’s

case. Poole had reportedly bragged to inmates that he had committed the rapes

for which Cotton was serving time.

The second trial was even more devastating than the first. Both victims testified

against Cotton; the jury did not believe

that Poole was the real assailant; and,

most damaging of all, the court withheld

evidence of Poole’s alleged confessions.

Convicted of both rapes, Cotton received

two life sentences plus 55 years in prison.

Back in prison, Cotton “waited it out” for

years. In 1994, however, he learned about

DNA testing (a procedure unavailable at

the time of his trials). He filed and won

a motion for DNA testing. In 1995,

Burlington police turned over to the

court all case evidence containing semen

or other bodily fluids. Samples from

Jennifer Thompson had deteriorated and

could not be tested, but those from the

second victim provided a breakthrough

for Cotton. On a tiny vaginal swab, scientists found a bit of sperm. Subjected to

PCR testing, that sample showed no

match to Ronald Cotton. He could not

have committed the crime.

The state DNA database matched the

sample to Bobby Poole. On June 30,

1995, almost 11 years after the rapes and

101

/2 years after being taken into custody,

Ronald Cotton was cleared of all charges

and released from prison.

Postconviction DNA

Testing

V

ictims and surviving family members confront a number of issues

and events following the conviction

and sentencing of a defendant. The impact of the crime does not end with the

incarceration of the offender. Convicted

defendants have the right to appeal their

sentences, the opportunity for parole, and

the ability to file subsequent requests for

additional DNA testing. All of these

postconviction events are upsetting to

victims and families and serve as painful

reminders of the suffering and loss associated with the crime. It is extremely important that crime victims and family

members are approached with great sensitivity. This is especially critical when the

conviction was based primarily on eyewitness identification by the victim. Victim

service providers must be aware that victims and their families may need special

services to help them cope with postconviction developments.

In the context of postconviction DNA

testing, it is important to realize that if a

convicted offender requests DNA testing

UNDERSTANDING DNA EVIDENCE: A GUIDE FOR VICTIM SERVICE PROVIDERS
of old or newly discovered evidence, this

does not mean the request will be granted. Postconviction requests, in which

DNA evidence is available for testing and

the test results are likely to exonerate an

offender, should be handled with great

care because it may be necessary to obtain

samples from victims and third parties for

the testing process. Prosecutors and victim service providers should ensure that

victim counseling resources are available

through their offices or a communitybased assistance program.

If testing results produce exculpatory 

evidence, particularly in mistaken eyewitness identification cases, victims may

still believe the defendant is guilty.

Victims may be upset and angry. For example, the credibility of sexual assault

victims is usually attacked in trial, and a

conviction is viewed as a significant validation of their credibility. To face having

their credibility called into question again

can cause tremendous distress. In addition, some victims may feel terribly guilty

about their part in convicting an innocent person. Reassure the victim that she

did the best she could at the time and

that memory can be fallible. It may help

to remind the victim that DNA technology, which may not have been available

at the time of the original investigation,

is an important tool in making sure the

right person is convicted. Remind the

victim or survivor that the criminal justice system is not perfect, and emphasize

the importance of knowing the truth and

identifying the right perpetrator to ensure

justice and prevent future victimization of

other individuals.

Also, it may help to inform victims of the

following:

■ Even the Innocence Project, which

uses DNA testing to exonerate persons who have been wrongfully convicted, concedes that in many cases

in which postconviction requests are

made for DNA testing, the results

have confirmed the identity of the

convicted person as the true perpetrator. This confirmation may have a

significant impact on decisions regarding the perpetrator’s probation

or parole.

■ The victim should be assured that

everyone in the system, particularly

prosecutors and judges, will make

sure that ambiguous results that do

not clearly exonerate the perpetrator

will not weaken the conviction or

result in a new trial.

■ If postconviction testing of DNA

evidence results in a valid exclusion,

the victim can be reassured that

growing DNA databases will increase the likelihood of identifying

the true perpetrator. DNA databases

also will make it easier to accurately

identify and link perpetrators in future cases.

Meanwhile, a number of states have

passed victims’ rights statutes that require

notification of victims, including notification of appeal proceedings, prison release,

application for pardon, or commutation

of sentence. Agencies involved in postconviction DNA cases should make certain they comply with applicable state

statutes.

Conclusion

T

he importance of the role forensic

DNA evidence plays in solving sexual assault and homicide cases cannot be overstated. DNA evidence is a

crucial tool used in effective police work

to solve violent crimes. For those who

have been wrongly accused, sentenced,

and imprisoned—sometimes for many

years—for a crime they did not commit,

DNA evidence exonerates the innocent

and alerts law enforcement to pursue the

true offender. By convicting the guilty

and freeing the innocent, DNA evidence

truly serves the interests of justice.

Although DNA is a powerful tool, it is

useless to the criminal justice system if

not properly collected, preserved, and

tested. Members of the criminal justice

community must be trained to identify

DNA evidence, to understand its significance, and to counsel victims on how

valuable it is in apprehending and convicting offenders.

As technology to test forensic DNA evidence advances and huge backlogs of rape

kits decline in laboratories nationwide,

crimes will be solved more quickly and

comparisons between known offenders

and unsolved cases will increase using the

FBI’s CODIS database.

For too long, victims of violent crime

have been ignored, but the criminal justice community now has an amazing tool

that will offer victims relief, peace of

mind, and some closure for having experienced and survived brutal sexual crimes

or the death of a loved one. Victim service providers, law enforcement, evidence

technicians, prosecutors, and others involved in bringing justice to crime victims are at the forefront of the DNA

revolution, and they must strive to educate the public about the vital role DNA

plays in protecting victims from further

trauma.

Glossary

T

his glossary highlights some of the

technological terms victim service

providers may encounter when dealing with victims during a criminal investigation. Many terms have been used in

this bulletin, but others are listed to give

OVC Bulletin

8
9

providers a more thorough understanding

of the importance of DNA.

ABO Blood Typing: A commonly used

genetic typing test that uses antibodies to

detect variations on the surface of human

red blood cells. Individuals are typed as

having an A, B, O, or AB blood type by

testing liquid or stains from body fluids

(such as blood, saliva, vaginal secretions).

One out of every three randomly selected

pairs of people have the same ABO blood

type.

Amelogenin: A gene present on the X

and Y sex chromosomes that is used in

DNA identification testing to determine

the gender of the donor of the DNA of a

biological sample.

Biological Evidence: Evidence commonly

recovered from crime scenes in the form

of hair, tissue, bones, teeth, blood, or

other bodily fluids.

Chain of Custody: A record of individuals who have had physical possession of

the evidence and the process used to

maintain and document the chronological history of the evidence. Documents

should include the name or initials of

the individual collecting the evidence,

each person or entity subsequently having custody of it, the dates the items

were collected or transferred, where the

items were collected, the agency and

case number, the victim’s or suspect’s

name (if known), and a brief description

of the item.

CODIS: The Combined DNA Index

System is an electronic database of DNA

profiles obtained from evidence samples

from unsolved crimes and from known

individuals convicted of particular

crimes. Contributions to this database

are made through state crime laboratories and the data are maintained by the

FBI.

Contamination: The undesirable transfer of material to physical evidence

(DNA) from another source.

Degradation: The breaking down of

DNA into smaller fragments by chemical or physical processes. Degradation of

DNA may limit its use as evidence.

DNA: Deoxyribonucleic acid, often 

referred to as the “blueprint of life,” is

an organic substance found in nearly

all cells. DNA determines each person’s

individual characteristics. An individual’s DNA is unique except in identical

twins. DNA in the cell nucleus is the 

genetic material inherited from our 

biological parents. The shape of DNA

resembles a rope ladder that has been

twisted (double helix).

DNA Advisory Board (DAB): Created

under the DNA Identification Act of

1994, DAB established standards for

forensic DNA testing laboratories and

held its last meeting in fall 2000.

DNA Marker: A piece of DNA from a

known location in the DNA molecule,

which differs between people. The DNA

marker is used to identify the specific genetic variations an individual possesses.

DNA Profile: A set of genetic characteristics that results from forensic DNA

analysis of several DNA markers.

DNA Typing or Profiling: The process

of testing to identify DNA patterns or

types. In the forensic setting, this testing

is used to indicate parentage or to exclude

or include individuals as possible sources

of body fluid stains (blood, saliva, or

semen) and other biological evidence

(bones, teeth, or hair).

Elimination or Reference Sample: A

term used to describe a sample of known

source taken for comparison purposes. An

elimination sample is one of known

source taken from a person who had lawful access to the crime scene to be used

for comparison with evidence of the same

type. Examples of elimination samples include blood or cheek (buccal) swabs for

DNA analysis, fingerprints from occupants, tire tread impressions from police

vehicles, or footwear impressions from

emergency medical personnel. A reference sample is material of a verifiable/

documented source which shows an

association or link between an offender,

crime scene, and/or victim when compared with evidence of an unknown

source. For example, a carpet cutting

taken from a location suspected as the

point of transfer for comparison with the

fibers recovered from a suspect’s shoes, a

sample of paint removed from a suspect’s

vehicle to be compared with paint found

on a victim’s vehicle following an accident, or a sample of the suspect’s and/or

victim’s blood submitted for comparison

with a bloodstained shirt recovered as 

evidence.

Exclusion: A DNA test result indicating

that an individual is excluded as the

source of DNA evidence. In the context

of a criminal case, exclusion does not

necessarily mean a suspect is innocent.

Exemplar: A biological sample (such as

blood or saliva) collected from a known

individual to be used for comparison to

DNA test results from evidence samples.

Also referred to as a standard.

Inclusion: A DNA test result indicating

that an individual is not excluded as the

source of DNA evidence. In the context

of a criminal case, inclusion does not necessarily mean a suspect is guilty.

Inconclusive Results: A situation in

which no conclusion can be reached 

regarding testing done due to one of

many possible reasons (such as no results

UNDERSTANDING DNA EVIDENCE: A GUIDE FOR VICTIM SERVICE PROVIDERS
obtained, uninterpretable results obtained, no exemplar/standard available

for testing).

Locus (pl. loci): The specific physical location of a gene on a chromosome.

Mitochondrial DNA: DNA found in the

mitochondria in each cell of a body. The

sequencing of mitochondrial DNA can

link individuals descended from a common female ancestor.

Nuclear DNA: DNA found in the nucleus of a cell. DNA testing using RFLP,

DQA1 (DQa), PM, D1S80, or STRs

screen markers in nuclear DNA.

PCR: Polymerase chain reaction is a

process used in DNA identification testing in which one or more specific small

regions of the DNA are copied using a

DNA polymerase enzyme so that a sufficient amount of DNA is generated for

analysis. This process enables scientists to

obtain genetic information from small or

degraded specimens.

Polymorphism: Variations in DNA sequences in a population that are detected

in human DNA identification testing.

Reference Sample: See Elimination or

Reference Sample listing.

RFLP: Restriction fragment length polymorphism is a process used in DNA identification testing in which size (fragment

length) differences at specific regions of

the DNA are detected.

STR: Short tandem repeat(s) are small

regions of the DNA that contain short

segments (usually 2, 3, 4, or 5 bases long)

repeated several times in tandem (sideby-side). Thirteen STR sequences have

been selected as the genetic markers to be

used in CODIS.

Substrates: Any background material

upon which a biological sample has been

deposited (e.g., clothing, glass, wood, or

upholstery).

References

Connors, E., T. Lundregan, N. Miller, and

T. McEwen. 1996. Convicted by Juries,

Exonerated by Science: Case Studies in the

Use of DNA Evidence To Establish Innocence After Trial. Washington, DC: U.S.

Department of Justice, National Institute

of Justice.

Hammond, H.A., and C. Thomas Caskey.

1997. Automated DNA Typing: Method of

the Future? Washington, DC: U.S. Department of Justice, National Institute of

Justice.

Handbook of Forensic Services: Evidence

Examinations—DNA General. 1999.

Washington, DC: Federal Bureau of

Investigation.

Inman, K., and N. Rudin. 1997. An

Introduction to Forensic DNA Analysis.

Boca Raton, FL: CRC Press, Inc.

Ledray, L.E. 2000. Sexual Assault Nurse

Examiner (S.A.N.E.) Development and

Operation Guide. Washington, DC: U.S.

Department of Justice, Office for Victims

of Crime.

National Commission on the Future of

DNA Evidence. 1999. Postconviction

DNA Testing: Recommendations for

Handling Requests. Washington, DC: U.S.

Department of Justice, National Institute

of Justice.

National Commission on the Future of

DNA Evidence. 1999. What Every Law

Enforcement Officer Should Know About

DNA Evidence. Washington, DC: U.S.

Department of Justice, National Institute

of Justice.

National Research Council. 1992.

DNA Technology in Forensic Science.

Washington, DC: National Academy

Press.

National Research Council. 1996. The

Evaluation of Forensic DNA Evidence.

Washington, DC: National Academy

Press.

Weedn, V.W., and J.W. Hicks. 1998. The

Unrealized Potential of DNA Testing.

Washington, DC: U.S. Department of

Justice, National Institute of Justice.

For Further

Information

American Prosecutors Research 

Institute

99 Canal Center Plaza, Suite 510

Alexandria, VA 22314

703–549–4253

World Wide Web:

www.ndaa-apri.org/apri/Index.html

Federal Bureau of Investigation (FBI)

202–324–3000

World Wide Web: www.fbi.gov

National Center for Victims 

of Crime (NCVC)

2111 Wilson Boulevard, Suite 300

Arlington, VA 22201

703–276–2880

Emergency: 1–800–394–2255

E-mail: ncvc@ncvc.org

World Wide Web: www.ncvc.org

National Commission on the Future 

of DNA Evidence

National Institute of Justice

810 Seventh Street NW.

Seventh Floor

Washington, DC 20531

202–307–2942

World Wide Web:

www.ojp.usdoj.gov/nij/dna

OVC Bulletin

10
11

National Criminal Justice Reference 

Service (NCJRS)

P.O. Box 6000

Rockville, MD 20849–6000

1–800–851–3420 or 301–519–5500

TTY: 1–877–712–9279 (toll free) 

or 301–947–8374 (local)

Office for Victims of Crime (OVC)

U.S. Department of Justice

810 Seventh Street NW.

Eighth Floor

Washington, DC 20531

202–307–5983

Fax: 202–514–6383

World Wide Web: www.ojp.usdoj.gov/ovc

Office for Victims of Crime Resource 

Center (OVCRC)

P.O. Box 6000

Rockville, MD 20849–6000

1–800–627–6872 

TTY: 1–877–712–9279 (toll free)

World Wide Web: www.ncjrs.org

Rape, Abuse & Incest National 

Network (RAINN)

635–B Pennsylvania Avenue SE.

Washington, DC 20003

202–544–1034

National Hotline: 1–800–656–HOPE

Fax: 202–544–3556

E-mail: rainnmail@aol.com

World Wide Web: www.rainn.org

Sexual Assault Nurse Examiner 

(S.A.N.E.)-Sexual Assault Response 

Team (S.A.R.T.)

World Wide Web: www.sane-sart.com

This Web site, sponsored by the Sexual

Assault Resource Service (SARS) of

Minneapolis, Minnesota, provides 

information and technical assistance to

individuals and institutions interested in

developing new S.A.N.E.-S.A.R.T. programs or improving existing ones. SARS

established the Sexual Assault Nurse

Examiner Development and Operation

Guide,which offers users a multidisciplinary, victim-centered way of responding

to sexual assault victims.

Speaking Out About Rape, Inc. 

(SOAR)

69 East Pine Street

Orlando, FL 32801

407–836–9692

Fax: 407–836–9690

World Wide Web: www.soar99.org

Violence Against Women Office 

(VAWO)

U.S. Department of Justice

810 Seventh Street NW.

Washington, DC 20531

202–307–6026

Fax: 202–305–2589

World Wide Web:

www.ojp.usdoj.gov/vawo

The Violence Against Women Office

(VAWO) was created in 1995 to implement the 1994 Violence Against Women

Act (VAWA) and to lead the national effort to stop domestic violence, sexual assault, and stalking of women. VAWO

works with victim advocates and law enforcement to develop grant programs that

support a variety of services for women,

including advocacy, emergency shelter,

law enforcement protection, and legal

aid. Two critical VAWO grants are the

STOP (Services*Training*Officers*

Prosecutors) Violence Against Women

Formula Grants and the STOP Violence

Against Indian Women Discretionary

Grants.

The STOP (Services*Training*

Officers*Prosecutors) Violence Against

Women Formula Grants are awarded to

the states, District of Columbia, and territories to develop and strengthen their

criminal justice system’s response to violence against women and to support and

enhance services for victims. Each

grantee must allocate at least 25 percent

of the grant funds to law enforcement, at

least 25 percent to prosecution, at least

30 percent to victim services, and at least

5 percent to courts. The remaining 15

percent can be allocated at each grantee’s

discretion within the broad parameters 

established by VAWA.

The STOP Violence Against Indian

Women Discretionary Grants are awarded to develop and strengthen tribal law

enforcement and prosecution efforts to

combat violence against native women

and develop and enhance services for victims. Tribes that have law enforcement

and prosecution responsibilities must allocate at least 25 percent of their grant

funds to tribal law enforcement, at least

25 percent to tribal prosecution, at least

30 percent to victim services, and at least

5 percent to courts. The remaining 15

percent can be allocated at each grantee’s

discretion within the broad parameters established by VAWA.

UNDERSTANDING DNA EVIDENCE: A GUIDE FOR VICTIM SERVICE PROVIDERS
U.S. Department of Justice

Office of Justice Programs

Office for Victims of Crime

Washington, DC 20531

Official Business

Penalty for Private Use $300

PRESORTED STANDARD

POSTAGE & FEES PAID

DOJ/OVC

PERMIT NO. G–91

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OVC Bulletin

Preparation of this document was supported by the Office for Victims of

Crime, Office of Justice Programs, U.S.

Department of Justice.The opinions, findings, conclusions, and recommendations

expressed in this document are those of

the author and do not necessarily represent the official position or policies of the

U.S. Department of Justice.

The Office for Victims of Crime is a component of the Office of Justice Programs,

which also includes the Bureau of Justice

Assistance, the Bureau of Justice Statistics,

the National Institute of Justice, and the

Office of Juvenile Justice and Delinquency

Prevention.

Acknowledgments

Kathryn McKay Turman joined the Office for Victims of Crime in July 1998.

She served as 1 of 22 Commissioners appointed to the National Commission

on the Future of DNA Evidence. From 1994 to 1998, she was Chief of the

Victim Witness Assistance Unit in the U.S. Attorney’s Office for the District 

of Columbia. As head of that unit, she oversaw services to about 10,000 victims

a year, ranging from victims of misdemeanor crimes to international terrorism.

From 1991 to 1993, she served as Director of the Justice Department’s Missing

and Exploited Children’s Program. Prior to joining the U.S. Department of

Justice in 1991, she was Special Assistant to the late U.S. Senator John Heinz.

She is a social worker and a graduate of the University of Texas at Austin. She

gives special thanks and recognition to Chris Asplen and Dr. Lisa Forman, both

of the National Commission on the Future of DNA Evidence, lead writer/editor

Theodosia Craig, and contributing writer/editor Nancy Walsh.