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DNA Answers

For technical assistance regarding forensic DNA and crime victims, email DNAanswers@ncvc.org.

Frequently Asked Questions

Frequently Asked Questions for Victim Service Providers about Forensic DNA

  1. What is a DNA profile?

  2. Can anyone learn about my medical and genetic history from this profile? 

  3. What is CODIS and what information does it contain? 

  4. What is the purpose of a sexual assault medical forensic exam? 

  5. Why do victims need to provide DNA samples?

  6. What happens to the DNA of a victim and other reference samples after they are collected? 

  7. How much does DNA testing cost?

  8. Victim service providers sometimes work with victims who were raped a number of years ago and then suddenly find out from law enforcement that the perpetr

    ator in their cases has now been identified through DNA. What kinds of emotions might these victims be feeling and how can they be helped? 

  9. How can victim service providers support a victim whose convicted offenders were exonerated by post-conviction DNA testing? How can victim service providers explain to victims why DNA testing takes so long? How can a victim find out the status of a sexual assault evidence kit? 

  10. Why are there times when the police cannot find a victim's sexual assault evidence kit? 

  11. Sometimes victims report a crime, but there is no effort to collect DNA evidence. Why not? 

  12. How can victims and victim service providers find out if their states have a sexual assault evidence kit backlog? 

  13. What can victims or victim service providers do if the police department will not send a victim's kit to the crime lab? 

  14. Is there someone they can contact? 

  15. What happens if a victim did not report a rape but kept the clothes and/or bedding from the night of the crime? Can these items be used as evidence? Why or why not?


  1. What is a DNA profile? Can anyone learn about my medical and genetic history from this profile?

    DNA profiles created for criminal justice purposes contain a certain set of identifiers or characteristics, which are found at specific points--called loci--on the DNA molecule. Information from 13 of these loci makes a DNA profile, and, much like a fingerprint, the features of DNA profiles can be compared to other DNA profiles for genetic matches. When the DNA profile is entered into the national DNA database (see #2 below), it appears as a series of numbers. DNA profiles do not reveal information about a person's physical traits such as race, age, or medical conditions.

  2. What is CODIS and what information does it contain?

    The Combined DNA Index System, or CODIS, is an FBI-managed system of national, state, and local databases that allows crime laboratory personnel across the country to compare DNA profiles from known criminal offenders (and arrestees where required by statute) with biological evidence from crime scenes.

    CODIS has proven crucial to solving crimes in which the offender's identity is unknown. By matching DNA profiles from different crimes, CODIS can link crimes to each other and identify serial offenders. CODIS can also match DNA profiles of unidentified human remains to DNA profiles from missing persons or their close family members and thus help identify the remains.

    Each record in CODIS contains information about the lab that entered the profile, an identifier for the DNA specimen, and the results of the DNA testing or the DNA profile. Other than the DNA profile, CODIS does not contain any other information that identifies the source of the profile. In other words, the CODIS database does not contain names, dates of birth, Social Security numbers, or any other personal identifier. CODIS follows strict rules that protect individual privacy and does not contain DNA profiles of crime victims.

  3. What is the purpose of a sexual assault medical forensic exam?

    Sexual assault victims who report the crime to the police or go to the hospital after an assault may be asked if they would like to have a medical forensic examination. One component of this examination is the collection of evidence, which may be analyzed to determine if DNA from the assailant is present on the victim's body, clothes, or other items the perpetrator may have touched. In cases in which the offender's identity is unknown to the victim, crime labs may be able to create a DNA profile of the offender and enter it into the national DNA database to help identify a suspect. During the examination, medical professionals will also document and photograph physical trauma and injuries that may have been inflicted at the time of the assault. This type of evidence may be helpful in cases where the perpetrator is known to the victim. Victims may also have been exposed to sexually transmitted infections as a result of the assault. These medical professionals--often specially trained nurses called Sexual Assault Forensic Examiners (SAFE) or Sexual Assault Nurse Examiners (SANE)--can administer or prescribe medications that may help protect a victim from a sexually transmitted infection and pregnancy. SAFEs and SANEs are trained to provide compassionate care to survivors while collecting evidence during a sexual assault forensic exam to minimize the trauma associated with the process.

  4. Why do victims need to provide DNA samples?

    Investigators may ask victims and others present at the crime scene to provide a DNA sample, called a "reference sample." These samples are used to determine if DNA found at the crime scene belongs to the victim or anyone else who was legitimately at the scene, or if it might belong to the perpetrator. In sexual assault cases, reference samples may be needed from any individual with whom the victim had consensual sex during the previous days (the number of days varies from jurisdiction to jurisdiction). The victim's DNA profile is used only to distinguish it from the DNA profile of the perpetrator. Victims' DNA profiles and other DNA profiles taken for exclusion (such as those from the victim's consensual sex partner) are not uploaded into CODIS.

  5. What happens to the DNA of a victim and other reference samples after they are collected?

    There currently is no uniform practice regarding what crime labs do with victim and reference samples after testing. Some public labs do retain victims' and other reference samples indefinitely. Many return the sample to the law enforcement agency that submitted it for testing, but retain the digitalized DNA profile. In many instances, the evidence becomes the property of the jurisdiction investigating the case.

  6. How much does DNA testing cost?

    DNA testing costs vary from case to case. These costs depend on many factors, including whether the testing is done by a private or public lab, how many potential perpetrators are involved, how many pieces of evidence are being tested, and what type of evidence is being analyzed. A sexual assault evidence kit can cost between $500 and $1,200 to analyze. Sexual assault evidence kits can be more expensive than other types of evidence to analyze because the victim's and the offender's DNA may get mixed together and must first be separated in order to analyze the offender's DNA profile. Testing bed linens, clothing, and other items incur additional costs.

  7. Victim service providers sometimes work with victims who were raped a number of years ago and then suddenly find out from law enforcement that the perpetrator in their cases has now been identified through DNA. What kinds of emotions might these victims be feeling and how can they be helped?

    Reopening an old case can bring out many different emotions in victims. Some victims will be relieved that a DNA match has resulted in identifying the assailant in the case. A victim may feel grateful that law enforcement has not forgotten about the case, and may fully participate in the criminal justice process. Victims in other cases may view the news as an unwelcome intrusion that feels like ripping open an old wound, and they may feel angry. Some victims have moved forward with their lives, gotten married, had children, moved, and experienced many other changes that make them unwilling to revisit the crime. A survivor may also be fearful of the criminal justice system. Victim service providers should be prepared to provide information about available services, counseling, victims' rights, and applying for victim compensation (many states will now provide compensation in past cases which have been reopened). For the most part, supporting a victim in these types of cases requires the same skills and information that victim services providers use in their daily work with survivors in current cases.

  8. How can victim service providers support a victim whose convicted offenders were exonerated by post-conviction DNA testing?

    Learning about an exoneration in their cases can be very traumatic for victims. Those working with victims or loved ones and friends should be prepared for a variety of responses. Most victims will react to this news with shock and disbelief. They may feel a strong sense of guilt and anguish over their part in the process. They may be angry, fearful, frustrated, and feel as if they are being re-victimized. Victim service providers should be prepared to provide support, referrals, and information about victims' rights. Victims will often have many questions and need a lot of information. To learn more about working with these victims, please visit our full-length brochure on this topic at www.ncvc.org/dna.

  9. How can victim service providers explain to victims why DNA testing takes so long?

    Many factors contribute to the amount of time it takes to test DNA in a criminal case. Crime laboratories that perform DNA testing may be underfunded and have large caseloads and limited trained personnel to perform the testing. So, the labs must prioritize cases. Labs generally analyze evidence from cases that are about to go to court first because the information is needed for trial. DNA testing in cases that have a known suspect, such as acquaintance rape cases, often falls to the bottom of the pile because DNA is not needed to discover the perpetrator's identity. Another factor that may contribute to delays is that DNA testing, especially in sexual assault cases, may be complicated and takes time to conduct. 

    Victims may feel understandably angry that DNA testing is taking a long time, but knowing the reason for the delay may help alleviate some frustration and confusion. It may also help to make the delay feel less personal.

  10. How can a victim find out the status of a sexual assault evidence kit?

    A victim should start by calling the police precinct where the crime was reported, beginning with the detective who handled the case, especially if the survivor has a prior relationship with him or her. If the case has been assigned to a new detective, the victim can call and establish a relationship with the new investigator. Victims can also connect with a victim advocate in the department to request help in finding out about the status of a sexual assault kit. Another option is contacting a community-based advocate in a local rape crisis center. Local rape crisis centers often have a working relationship with the detectives who investigate sexually related crimes and can help pave the way. Victims may also consider calling the district attorney's office and talking to a victim witness coordinator in that office.

  11. Why are there times when the police cannot find a victim's sexual assault evidence kit?

    Law enforcement agencies may not be able to locate a rape kit for many reasons that vary from place to place. Most jurisdictions across the country do not have easy and efficient tracking systems for all of their evidence. In many cases, evidence is logged into simple paper notebooks that have to be manually searched to locate a piece of evidence. In some jurisdictions, evidence storage units may be full of old evidence that may be piled on floor-to-ceiling shelves. When cases are years old, finding the kit becomes even more complicated. Many states do not have evidence retention laws that cover evidence not connected to an active investigation, and evidence storage is limited. Unfortunately, in some cases, the evidence may have been destroyed. Additionally, if the statute of limitations has expired in the case or the precinct decided not to proceed with a case, the kit may have been destroyed.

  12. Sometimes victims report a crime, but there is no effort to collect DNA evidence. Why not?

    DNA evidence may not be available or useful in every case. If a perpetrator takes certain precautions, he or she may leave behind little or no trace of biological material that could include DNA. The crime scene may have been contaminated so that forensic evidence no longer exists or is not usable. The availability of other evidence in certain cases may make DNA analysis unnecessary. State law or protocols regarding the timing of evidence collection may prelude collection in some instances. In some cases, investigators may simply lack training or resources for DNA collection and testing. However, a lack of resources for testing should not prohibit DNA collection: financial support for analyzing DNA evidence is available through the federal government. See www.dna.gov for funding opportunities.

  13. How can victims and victim service providers find out if their states have a sexual assault evidence kit backlog?

    In the United States at this time, there is no state-by-state, up-to-date, comprehensive tracking system for sexual assault evidence kits. The federal government has attempted several times to estimate the number of kits that are awaiting DNA testing; reports from these projects can be found at www.dna.gov and www.ncjrs.org. Victims or providers can check with their local police departments to find out if their state or local jurisdiction has a backlog of sexual assault evidence kits. Victims or providers can ask the police if they believe they have any kits that have never been sent to the lab for testing in their jurisdiction. They may also want to ask about their police department's policies on sexual assault evidence kit testing. Depending on the department's policy, there is a chance that some kits were never forwarded for testing and will be lingering in evidence storage facilities. Victims or providers can also call the local or state crime lab to find out if they have any unanalyzed kits in their possession. Finally, they can search online news sources for stories about untested sexual assault kits or ask local news stations to look into the issue.

  14. What can victims or victim service providers do if the police department will not send a victim's kit to the crime lab? Is there someone they can contact?

    First, they can talk to the detective in charge of the case and try to get a clear understanding of where the roadblock is and why the case is not moving forward. If the victim feels there is any information that the police do not have that may help advance the case, the victim can ask to meet with the detective to review the facts of the case. A victim or advocate may want to contact the prosecutor's office, as well. Ultimately, the decision to send evidence to be analyzed is that of law enforcement's, but a victim or victim service professional can certainly strongly advocate throughout the criminal justice system to have sexual assault evidence kits submitted to the lab.

  15. What happens if a victim did not report a rape but kept the clothes and/or bedding from the night of the crime? Can these items be used as evidence? Why or why not?

    In part, the answer depends on how the evidence has been stored. Evidence that has not been stored correctly may be contaminated or may have deteriorated. However, modern DNA technology now allows for testing of evidence that could not have been analyzed even 10 years ago. The "chain of custody" will also likely need to be addressed. This term refers to the process of documenting how evidence is collected, analyzed, stored, and protected from its initial collection at the crime scene all the way to its introduction as evidence before a court of law. Victims who want to find out if evidence they have kept can be used in a criminal case can call the local precinct and ask to speak to a detective who handles sexual assault crimes. Although law enforcement officer generally determines which evidence may be useful in an investigation, a victim may also want to contact the local prosecutor's office, as well. Victims who may be interested in pursuing a civil case (suing the perpetrator for damages in civil court) may also want to contact a private attorney to get some answers about the admissibility of such evidence in a civil case. Even in cases where DNA is not available, the items may have other evidentiary value.


This project was developed with funding under cooperative agreement 2009-SZ-B9-K010 awarded by the Office for Victims of Crime, Office of Justice Programs, U.S. Department of Justice. The opinions, findings, and conclusions or recommendations expressed herein are those of the contributors and do not necessarily represent the official position or policies of the U.S. Department of Justice.