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Investigative genetic genealogy FAQs

From ISOGG Wiki

These frequently asked questions (FAQs) on investigative genetic genealogy (IGG) provide information on domain vocabulary and definition; what is done, by whom, and how; and links to selected policies. The FAQs are a work in progress. Comments, corrections and further questions are welcome.



What is investigative genetic genealogy?

Investigative genetic genealogy (sometimes also known as forensic genetic genealogy) is the science of using genetic and genealogical methods to generate leads for law enforcement entities investigating crimes and identifying human remains. Genetic genealogists use DNA profiles from a crime scene or from unidentified human remains to identify close genetic DNA profiles or matches. By comparing the known genealogy of those close familial matches, this constrains the number of possible close relatives of the perpetrator or victim. Such efforts enable investigators or researchers to more closely focus their investigation in cold or stale criminal cases providing new leads.[1][2]

This investigative or forensic genetic genealogy technique came to public attention after the arrest of the the so called "Golden State Killer" in April 2018. By October 2019 more than 60 cold cases had been solved in this manner.[3][4]

What is forensic genealogy and how is it different from investigative genetic genealogy?

Forensic genealogy is a term used particularly in the US to describe the application of genealogical methods in cases which have legal implications, eg heir hunting, establishing citizenship, etc. IGG is a subset of forensic genealogy and not a synonym.[5][6]:337

Which genetic genealogy databases are used?

The two databases which are known have been used to date for IGG are: GEDmatch and Family Tree DNA. A third database DNA Solves, which is reserved solely for law enforcement cases, was launched in December 2019 by Othram, a forensic genome sequencing company.[7]

Can law enforcement agencies access the databases of 23andMe, AncestryDNA, GEDMATCH, FamilyTreeDNA, MyHeritage DNA, Living DNA and other DNA databases?

The short answer is yes, but only with a proper, legal and lawful search warrant signed by a judge. In the United States, search warrants can be challenged or limited in focus by a legal appeal process. As of January 2020 the following genetic genealogy companies provide information in their terms of service or privacy notices regarding possible law enforcement access. Bold print added below for emphasis.


23andMe have stated in their privacy policy the following;
Access to your information
" We will not provide information to law enforcement or regulatory authorities unless required by law to comply with a valid court order, subpoena, or search warrant for genetic or Personal Information."

Section E. As required by law "Under certain circumstances your Personal Information may be subject to processing pursuant to laws, regulations, judicial or other government subpoenas, warrants, or orders. For example, we may be required to disclose Personal Information in coordination with regulatory authorities in response to lawful requests by public authorities, including to meet national security or law enforcement requirements. 23andMe will preserve and disclose any and all information to law enforcement agencies or others if required to do so by law or in the good faith belief that such preservation or disclosure is reasonably necessary to: (a) comply with legal or regulatory process (such as a judicial proceeding, court order, or government inquiry) or obligations that 23andMe may owe pursuant to ethical and other professional rules, laws, and regulations; (b) enforce the 23andMe Terms of Service and other policies; (c) respond to claims that any content violates the rights of third parties; or (d) protect the rights, property, or personal safety of 23andMe, its employees, its users, its clients, and the public."

23andMe have further clarified in a blog post that they "would use every legal remedy possible" to challenge a request for access.

23andMe also caution their customers about the risks of uploading raw data to third-party services.


AncestryDNA say in their privacy policy that;

Law Enforcement
Ancestry does not voluntarily cooperate with law enforcement. To provide our Users with the greatest protection under the law, we require all government agencies follow valid legal process.

If we are compelled to disclose your Personal Information to law enforcement, we will do our best to provide you with advance notice, unless we are prohibited under the law from doing so. In the interest of transparency, Ancestry produces a Transparency Report where we list the number of valid law enforcement requests for user data across all our sites.

Other Legal or Regulatory Process
We may share your Personal Information if we believe it is reasonably necessary to:
Comply with valid legal process (e.g., subpoenas, warrants); ...

They further stated in a blog post that they will "always advocate for our customers’ privacy and seek to narrow the scope of any compelled disclosure, or even eliminate it entirely".

FamilyTree DNA

FamilyTree DNA reports in their Terms of Service, in section 6b;

You understand that depending on your settings your information may be compared with genetic information submitted by Law Enforcement Accounts to assist in the identification of deceased individuals or the identification of possible suspects in crimes involving homicide, sexual assault, or child abduction (“Violent Crimes”). Please see our Privacy Policy for more information regarding the use of the Services for law enforcement matching;

You agree to not use the Services for any forensic examinations, criminal investigations, and/or similar purposes (“Law Enforcement Purposes”) without a jurisdictionally valid subpoena, issued in connection with an official criminal investigation, a court order, or a search warrant properly issued under the procedures described in the Federal Rules of Criminal Procedure or equivalent state warrant procedures, based on a showing of probable cause (“Legal Process Documentation”), or written permission from FamilyTreeDNA following a request that meets our requirements to register as a law enforcement user;

You agree to not use the Services for any law enforcement purposes, forensic examinations, criminal investigations, and/or similar purposes without the required legal documentation and written permission from FamilyTreeDNA;

In section C: FamilyTreeDNA User Conduct - Unlawful and Prohibited Use of the Services:
As a requirement of your use of the Services, you guarantee to FamilyTreeDNA that you will not use the Services for any function that is unlawful or prohibited by these terms. Using the Services for law enforcement purposes without the authorized permission of FamilyTreeDNA or pursuant to valid Legal Process Documentation, further explained in our Law Enforcement Guidelines, is strictly prohibited. Users wanting to create an account for law enforcement purposes are required to register all DNA samples and genetic files in advance of processing and use of the Service. Use of the Service for law enforcement purposes is a privilege, not a right. FamilyTreeDNA will track all files uploaded by registered law enforcement user accounts to ensure they are properly identified as such. FamilyTreeDNA reserves the right to revoke law enforcement’s account access for any reason without warning, including any use of the account for any law enforcement purpose not expressly agreed to by FamilyTreeDNA.


GEDMATCH is not a DNA testing company, but provides data analysis from raw data uploaded by its user members. It is helpful in Its autosomal DNA (atDNA) search matching allowing members to compare member-uploaded raw data that was tested at different DNA testing companies. Their Terms of Service state;

Raw DNA Data Provided to GEDmatch
When you upload Raw Data to GEDmatch, you agree that the Raw Data is one of the following:
Your DNA;
DNA of a person for whom you are a legal guardian;
DNA of a person who has granted you specific authorization to upload their DNA to GEDmatch;
DNA of a person known by you to be deceased;
DNA obtained and authorized by law enforcement to identify a perpetrator of a violent crime against another individual, where 'violent crime' is defined as murder, nonnegligent manslaughter, aggravated rape, robbery, or aggravated assault ;
DNA obtained and authorized by law enforcement to identify remains of a deceased individual;
An artificial DNA kit (if and only if: (1) it is intended for research purposes; and (2) it is not used to identify anyone in the GEDmatch database); or DNA obtained from an artifact (if and only if: (1) you have a reasonable belief that the Raw Data is DNA from a previous owner or user of the artifact rather than from a living individual; and (2) that previous owner or user of the artifact is known to you to be deceased).

By registering for GEDmatch and using the Site, you agree that you will not upload Raw Data that does not satisfy one of these categories. If you have previously uploaded Raw Data that does not satisfy one of these categories, you hereby agree that you will remove it immediately.

GEDmatch will not be responsible for any Raw Data provided to GEDmatch in violation of this Policy. Violators of this Policy will have their Raw Data or other personal information deleted without warning, their access will be blocked, and/or other remedial steps may be taken, including any legal action allowed under law.

Living DNA

Living DNA state in their privacy statement that;

3. The Legal Process
There are circumstances in which we may be legally required to disclose information. Examples of this include where we are subject to a binding court order, subpoena, or a legally binding direction by a regulator, and where we are required to share information with HM Revenue and Customs. We reserve the right to share personal information where we reasonably believe that we are legally required to do so. We will not share your personal information with law enforcement agencies unless we believe that we are legally compelled to do so. We may also share information where this is necessary for us to exercise or enforce our rights under our Terms or otherwise at law, or where we reasonably and in good faith consider it necessary or appropriate to do so in order to protect the security of our site, customers or employees.:

3. Where necessary to comply with a legal obligation. We have shortened this to 'comply with law'.


MyHeritage say in their privacy policy that:

Will MyHeritage Disclose any of Your Personal Information to Third Parties?
We will not provide information to law enforcement unless required by a valid court order or subpoena for genetic personal information.

We may share your personal information only in very limited circumstances:
When legally required

How can we find out if a company has received a request for access to personal information from law enforcement?

Some of the companies publish transparency reports which list requests for data access received from law enforcement.

Transparency reports are currently published by 23andMe, AncestryDNA and FamilyTree DNA:

How does law enforcement matching work at GEDmatch

Law enforcement can upload DNA profiles to GEDmatch in compliance with the terms and conditions outlined in the site policy.

How does law enforcement matching work at FamilyTreeDNA?

See the FamilyTreeDNA FAQs on law enforcement matching and the FamilyTreeDNA Law Enforcement Guide.

Do the police have access to my DNA?

They don't. And they never will. Or at least not to your raw DNA data. What they see is your user name, your e-mail address and the amount of DNA you share with your match. They can use a chromosome browser to view the location of the shared segments of DNA. You never see anyone's raw DNA data (unless they specifically give you access to it) and neither do the police.

Which countries are using investigative genetic genealogy?

As of February 2020 the method has been mostly used by law enforcement agencies in the US. The police in Vancouver, Canada, announced in May 2019 that they were using genetic genealogy and had hired the services of Parabon. The police in Edmonton, Alberta, announced in February 2020 that they would be starting to use genetic genealogy.

Pilot studies are under way in some other countries (the Netherlands, Sweden and Australia). The Swedish Police Authority has published a detailed report on its pilot study. The report Forensic DNA traces and genealogy can be downloaded in English and Swedish from the Swedish Police Authority's website. On the publications page scroll about two thirds of the way down the page to locate the link.

FamilyTreeDNA currently restricts the use of their database to law enforcement agencies in the US but the database has been used for two pilot studies in Sweden. The GEDmatch database could potentially be used by law enforcement agencies worldwide.

I want to share my DNA for law enforcement purposes. What should I do?

I do not live in the US. Will US law enforcement agencies have access to my DNA profile?

The police will only have access to your profile at GEDmatch or at FTDNA if you are opted in to law enforcement matching. At GEDmatch all users were automatically opted out with effect from May 2019 and had to opt in to law enforcement matching. Following the sale of GEDmatch to Verogen in December 2019, all EU customers were again required to re-consent to their use of the database under the new owners. FTDNA customers are automatically opted in to law enforcement matching. Users in the European Union were retrospectively opted out in March 2019, but new EU users are automatically opted in. However customers retain the right to change these automatic options at any time.

I have not taken a DNA test? Could I be involved in an investigation?

Yes. Your genealogical data or other public information could be used as part of the investigation if you have a relative in the GEDmatch or FTDNA database. You might be contacted by the police for information about your family tree or you might be approached for target testing to narrow down the search pool. For practical purposes you are not likely to be affected unless you have a cousin in the database who is a close match (eg fourth cousin or closer) with the DNA from the crime scene or with the DNA of the unidentified human remains.

What are vendor policies concerning investigative genetic genealogy?

The FamilyTreeDNA Law Enforcement Guide restricts the use of the database in the US to the following cases:

  • To identify the remains of a deceased individual
  • To identify a perpetrator of homicide, sexual assault, or abduction

The GEDmatch Site Policy only allows uploads of DNA profiles for the following purposes:

  • DNA obtained and authorized by law enforcement to identify a perpetrator of a violent crime against another individual, where 'violent crime' is defined as murder, nonnegligent manslaughter, aggravated rape, robbery, or aggravated assault
  • DNA obtained and authorized by law enforcement to identify remains of a deceased individual

Technical details

Which companies and organisations offer investigative genetic genealogy services?

N.B. Inclusion on the list below does not imply endorsement by ISOGG. Law enforcement agencies are advised to make their own checks before investing in an IGG service.

The following companies are known to be offering investigative genetic genealogy services:

In addition, the FBI has its own investigative genetic genealogy unit in California. Some US law enforcement agencies have also established their own IGG units. Florida was the first state to have its own forensic genealogy unit. It is headed up by Lori Napolitano. See:

What type of testing is done?

There are many different methods used which rely of measuring lots of markers across the genome. These markers are used to build a SNP profile for upload to one of the genetic genealogy databases that allows law enforcement searches. Microarray testing can be successfully used if there is a high-quality single source profile but sequencing is generally preferred for forensic use and particularly when working with degraded DNA

Which companies offer microarray testing for investigative genetic genealogy?

N.B. Inclusion on the list below does not imply endorsement by ISOGG.

Which companies offer sequencing for investigative genetic genealogy?

N.B. Inclusion on the list below does not imply endorsement by ISOGG.

What sources of DNA are used?

Testing of DNA found at a crime scene is likely to be most successful for IGG if single source DNA is available in sufficient quantities from semen, blood or saliva.

For the identification of human remains the petrous bone in the inner ear yields the highest quantities of exogenous DNA.

In some cases it has been possible to extract nuclear DNA from rootless hair.

Are there any peer-reviewed publications about the extraction of nuclear DNA from hair?

The following articles have been published in the scientific literature:

Dr Ed Green at the University of California, Santa Cruz, has co-operated with several law enforcement agencies on a number of investigations.[8] However, his methods have not yet been subjected to peer review. Bode Technology also claim to be able to extract DNA from rootless hair.

Is it possible to extract DNA for genetic genealogy use from mixtures?

Two person mixtures can sometimes be analysed. Success will depend on the relative amounts of DNA from the major and minor contributors. A single-source DNA sample from the minor contributor is often needed to separate the two profiles. In rare cases three-person mixtures can be analysed if there are only trace contributions from the minor contributors. See:

The US National Institute of Standards and Technology (NIST) has published a draft report on "DNA Mixture Interpretation: A Scientific Foundation Review".

Are there any peer-reviewed publications on the methods used to extract a SNP set from whole genome sequencing data for upload to genetic genealogy databases?

Yes. Two papers have been published by Swedish scientists:

Which microarray chips are used?

Parabon uses the Illumina CytoSNP-850K chip (851,274 SNPs). For technical details see the Illumina website.

Are there any peer-reviewed papers investigating the use of microarrays on compromised DNA for investigative genetic genealogy?

De Vries et al have published a paper in Forensic Science International Genetics (2021) Impact of SNP microarray analysis of compromised DNA on kinship classification success in the context of investigative genetic genealogy.

There is a preprint from Russell et al (2021) on the Developmental validation of the Illumina Infinium Assay using the Global Screening Array (GSA) on the iScan System for use in forensic laboratories

How much DNA is required to generate a profile?

The minimum quantity of DNA required will vary depending on a number of factors including:

  • Quantity of DNA
  • Quality of DNA
  • Source of DNA
  • Contamination from non-human sources like bacteria
  • Mixtures

It also depends on the testing technology. Microarrays perform badly at low quantity and low quality and will fail on samples with more than 50% contamination. CODIS markers (autosomal STRs) work fine on contaminated DNA but also require fairly decent quality. Sequencing works well even if the DNA is so degraded that the fragments are as small as 40-50 bases.

In general terms, DNA profiles can be generated with >20 ng of DNA. In some situations the labs can work with quantities as low as 1 ng. Sequencing can also sometimes work with quantities as low as 150 pg of DNA. A John Doe from Snohomish County in Washington State was identified from a DNA sample of less than 200 pg extracted from a tooth.[9]


Are there any organisations which accredit genealogists?

There are a number of organisations around the world which provide accreditation for genealogists. These include:

New legislation in the US state of Maryland requires that all genealogists working on forensic cases should be licensed by 1st October 2024 though no details are as yet available as to how this licensing process will work. For further details see the blog post from Dick Eastman Maryland Now Requires Licensing of any Forensic Genealogist Who Works With Police.

Is accreditation a guarantee of quality?

There is no organisation which provides accreditation in genetic genealogy and accreditation from one of the above genealogical organisations is no guarantee that the practitioner has the relevant knowledge and expertise in genetic genealogy. There are many excellent genealogists who are not accredited with any of these organisations, including many of the leading practitioners of investigative genetic genealogy.

For a detailed overview of genealogical credentials see Credentials for Genealogists: Proof of the Professional (2nd edn) by Paul Gorry (Blessington Books, 2021). Available from Amazon.

Are there any best practice guidelines relating to genetic genealogy?

An ad hoc group of genetic genealogists compiled a set of Genetic Genealogy Standards in 2015. For background on the creation of the standards see the article by Debbie Parker Wayne Genetic genealogy journey: genetic genealogy standards (National Genealogical Society Magazine April-June 2015 41: 59-61). See also the blog post by Blaine Bettinger Announcing the genetic genealogy standards. The Genetic Genealogist, 10 January 2015.

The US-based Board for the Certification of Genealogists has published a book of Genealogy Standards (2nd edition, 2019) which includes standards on the interpretation of DNA results for genetic genealogy. For a discussion of the DNA-related standards see the series of eight blog posts on DNA standards written by Debbie Parker Wayne.

There are no published genealogy standards for best practices in investigative genetic genealogy. The companies and law enforcement agencies who perform the genealogy searches may have developed their own internal guidelines.

Legal issues

What is the Fourth Amendment? Does it protect me?

The Fourth Amendment is a clause in the US Constitution which establishes the “right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures” by the government. It protects all US citizens and others within the jurisdiction of the United States.[10]

The following legal scholars have written opinion pieces on investigative genetic genealogy in general and the implications of the Fourth Amendment (note that essays in legal journals do not undergo peer review):

What is third party doctrine?

The third-party doctrine is a US legal doctrine which holds that voluntarily sharing information with a third party such as a genetic genealogy company means that the individual has “no reasonable expectation of privacy”. Such sharing renders the information beyond the protections of the Fourth Amendment. For further details see the article by Steven J Arango for the American Bar Association The third-party doctrine in the wake of a “seismic shift".

What is Carpenter versus the United States?

Carpenter v. United States was a landmark court case in the US which was decided by the Supreme Court in 2018 and which challenged the third party doctrine. The case related to a Fourth Amendment challenge to electronic database access under the personal control (such as by password or under contract) of a person. Carpenter challenged that his Fourth Amendment rights were violated when law enforcement accessed his personal, password-protected, cell phone database without a legal warrant. The USSC ruled that the access of GPS location information and tower ping codes which conflicted with Carpenter's defense and which led to his conviction was improper without a proper warrant.

For information on the possible implications of Carpenter v. United States for investigative genetic genealogy see: Ram, Natalie, Genetic privacy after Carpenter. Virginia Law Review 2019; 105. Forthcoming). Available at SSRN: or

What is GDPR? Does it protect me?

GDPR is the European Union’s General Data Protection Regulation. It gives EU residents the right to control how their data is used. Data must be processed fairly for specified purposes and on the basis of the consent of the person concerned or some other legitimate basis laid down by law. GDPR applies to all companies and organisations which have customers or members in an EU country. Individuals have the right to complain to the privacy regulator in the country in which they reside if they believe that their data has been used inappropriately. It is not known if an EU resident has complained to a regulator about the use of their data in a genetic genealogy database without their consent by US law enforcement agencies.


Is investigative genetic genealogy regulated?

There is currently no legal or regulatory oversight of investigative genetic genealogy in the US or elsewhere.

Are there any guidelines on how and when investigative genetic genealogy should be used?

The US Department of Justice issued an Interim Policy on Forensic Genetic Genealogical DNA Analysis and Searching in September 2019 which will take effect from 1st November 2019. A final department policy on forensic genetic genealogy will be issued in 2020. See here for the press release. In an editorial in Science, Thomas Callaghan, the FBI's Chief Biometric Scientist, encouraged members of the public to provide feedback to the FBI on the Interim Policy.

The American Society of Crime Lab Directors published a policy statement on genetic genealogy in October 2019.

SWGDAM (the Scientific Working Group on DNA Analysis Methods), which reports to the FBI Director, convened a Committee of Correspondence to advise it on the subject. They held a technical session on investigative genealogy at their meeting in July 2019 (the session was postponed from January 2019 because of the federal government shutdown). The committee was tasked with preparing a position statement on investigative genetic genealogy and recommending what future work, if any, SWGDAM should undertake on the subject. (See p4 of this document: The resulting document Overview of investigative genetic genealogy was published by SWGDAM on 18th February 2020.

The Sacramento County District Attorney's Office in California has a Memorandum of Understanding for Investigative Genetic Genealogy Searching.

A meeting of US stakeholders was held at the Banbury Center at the Cold Spring Harbor Laboratory in New York in October 2019 to discuss "Emerging Issues of Privacy, Trust, and Societal Benefit from Consumer Genomics". The meeting agenda can be found here. The Banbury Center have advised; "In terms of post-meeting outputs, the immediate communication about the meeting (the meeting agenda) will be on our website (, and we’ll tweet ( when it has been posted. Depending on the meeting discussions, and what the group agrees is the best forum for outputs, we’ll either post a summary report on our website (~30 days after the meeting), or if the group decides to write something more formal, it could be longer to allow for the writing/submission process."

The UK's Biometrics and Forensics Ethics Group published a report in September 2020 entitled Use of genetic genealogy techniques to assist with solving crimes which looked at the feasibility of using genetic genealogy methods for the identification of suspects in criminal cases in the UK.

The Forensic/Investigative Genetic Genealogy Project Working Group of the Australia New Zealand Policing Advisory Agency have developed some Principles for the application of forensic investigative genetic genealogy.

Have genetic genealogy methods been validated for forensic use?

So far just one study has been published in the UK which has validated the methods. See:

Are IGG methods relevant to a court trial of a criminal?

Thus far, IGG methods have not been relevant in an actual trial. DNA brought into court is obtained directly from the crime scene and the accused defendant. Genealogy investigations are important in identifying investigative leads, but are not evidence about the crime per se.

Have genetic genealogy methods been tested in court?

Both genetic and genealogy methods have been tested in court but the specific alignment of the two methodologies to generate investigative leads has not been tested in court.

Have any cases gone to trial where genetic genealogy was used to generate an investigative lead?

Yes. Genetic genealogy was used to identify William Earl Talbott as a suspect in the murder of a Canadian couple, Tanya Van Cuylenborg and Jay Cook, who were murdered in Washington State in the USA. The genetic genealogy was not presented as evidence but a statement about genetic genealogy was presented in court. The book The Forever Witness by Edward Humes ((Dutton, 2022) provides a detailed narrative overview of the Talbot case.

For further information on the Talbott case see the following links:

I have a complaint about the actions of a US law enforcement agency. Who should I write to?

See this article on the USA Gov website for information on how to file a complaint. Alternatively you can contact the American Civil Liberties Union.

Who provides oversight of the FBI?

According to the FBI website: "The FBI's activities are closely and regularly scrutinized by a variety of entities. Congress—through several oversight committees in the Senate and House—reviews the FBI’s budget appropriations, programs, and selected investigations. The results of FBI investigations are often reviewed by the judicial system during court proceedings. Within the U.S. Department of Justice, the FBI is responsible to the attorney general, and it reports its findings to U.S. Attorneys across the country. The FBI’s intelligence activities are overseen by the Director of National Intelligence."

Who is responsible for accrediting forensic service providers in the US?

Accreditation is the responsibility of the ANSI National Accreditation Board (ANAB). There is additional accreditation required by the FBI for CODIS labs, using what is known as the Quality Assurance Standards.


Are there are any organisations which provide guidance on ethical issues relating to forensic genetics?

In the UK ethical oversight is provided by the Biometrics and Forensics Ethics Group. There is also an independent London Policing Ethics Panel.

The Swedish Police Authority has an Ethics Board.

Can genetic genealogy be used to identify the mothers of baby does?

The identification of baby does is a controversial use of genetic genealogy but in the US there are no legal barriers to such usage. At GEDmatch the entire database is opted in to matching with all unidentified human remains cases including baby does. Only private and research kits are exempt. The following two articles provide background reading on this subject:

I am morally opposed to the death penalty. Can I restrict law enforcement access to my data to jurisdictions which do not use the death penalty?

No. Once you have opted in to law enforcement matching there is no facility to restrict access by country or jurisdiction. However FTDNA customers can opt out of law enforcement matching at any time.

Which countries use the death penalty?

142 countries have either abolished the death penalty in law or in practice. In 2018, most known executions took place in China, Iran, Saudi Arabia, Vietnam and Iraq. The following countries carried out executions between 2013 and 2017:

Afghanistan, Bahrain, Bangladesh, Belarus, Botswana, Chad, China, Egypt, Equatorial Guinea, India, Indonesia, Iran, Iraq, Japan, Jordan, Kuwait, Malaysia, Nigeria, North Korea, Oman, Pakistan, Palestinian Territories, Saudi Arabia, Singapore, Somalia, South Sudan, Sudan, Taiwan, Thailand (2018), United Arab Emirates, USA, Vietnam and Yemen. (Data is not available from Libya or Syria.)


Which US states still apply the death penalty and for what crimes?

As of May 2021 the death penalty is authorised in 27 states and can also be used by the federal government and the US military. Eleven of these states have not carried out an execution in the last decade, and in some cases for much longer.


Surveys and attitudes

What do the public think about the use of genetic genealogy databases by law enforcement?

Limited information is currently available about the public’s views on the use of genetic genealogy databases and further research in this area is necessary.


The following study included international participants but the majority of respondents were in Australia:

United Kingdom

YouGov polled 1,621 adults in Great Britain in October 2019 and found 55% of the population thought that the police should be able to access the DNA records of people held in private databases, The results were published in an article in the Daily Telegraph on 4 January 2020.

Two research papers have been published looking at the attitudes of UK stakeholders on the use of investigative genetic genealogy:


The Pew Research Center published a survey in February 2020 on the attitudes of US adults to sharing genetic data with law enforcement. 48% of Americans thought it was acceptable for DNA testing companies to share data with law enforcement, 33% were against and 18% were not sure. See the Pew Research article About half of Americans are OK with DNA testing companies sharing user data with law enforcement. This survey was part of a wider study into American attitudes to privacy which was first published in November 2019. See the Pew Research article: Americans and privacy: concerned, confused and feeling lack of control over their personal information.

Hazel et al published a qualitative research paper in 2021 on Direct-to-consumer genetic testing: Prospective users’ attitudes toward information about ancestry and biological relationships (PLOS ONE, published online 29 November 2021). The research was based on focus group interviews in Nashville, Tennessee.

Researchers at the Center for Medical Ethics and Health Policy at Baylor College of Medicine are undertaking a four-year research project starting in 2021 studying public preferences and policy options for genetic genealogy. See this blog post from ISHI news and the project page on the Baylor website.


An informal online survey on the genealogical use of DNA to identify unknown persons was conducted by genetic genealogist Maurice Gleeson in October and November 2018. There were 767 respondents. The results were published online in a blog post entitled How do you feel about your DNA being used by the police? - the results of a survey.

Forensic DNA databases

When does law enforcement turn to IGG to solve crimes?

DNA is routinely used to solve crimes. LE uses many methods to identify suspects. If these two methods do not converge on a suspect, LE may turn to IGG methods. However, in some of the cases where genetic genealogy has been used standard DNA testing techniques have not always been deployed (see below).

Do all prisoners in the US have their DNA in the national DNA database?

CODIS (the Combined DNA Index System) is the name often used to describe the police databases in the US. There are in fact three different databases: Local DNA Index Systems (LDIS) where DNA profiles originate, State DNA Index Systems (SDIS), and the National DNA Index System (NDIS) which allows states to compare DNA information with one another. The national database was implemented in October 1998.

In many states there were no retroactive laws requiring the testing of prisoners. It has been argued that testing this population is a matter of public safety. See:

Investigative genetic genealogy has identified suspects in a number of cases where the individual already had a criminal record and had been in prison but had not had their DNA tested. See the article by Jon Schuppe for NBC News A national disgrace; holes in DNA databases leave crimes unsolved for decades, 16 August 2020.

In two cases which were ultimately solved through IGG, the killers were executed without having their DNA taken even though the DNA collection was lawfully mandated at the time.

Are sexual assault kits in the US tested as a matter of routine?

No. There is a severe backlog of around 200,000 untested sexual assault kits. See:

In addition, even when the testing is done, hits in the CODIS database are not always followed up because there are inadequate resources for investigation and processing. See: Harmon R. Going beyond CODIS: the illusion of rape-kit testing as panacea. Forensic Magazine 23 December 2015. Retrieved from the Wayback Machine on 27 January 2020.

Do law enforcement agencies in the US have the ability to test the DNA of all convicted offenders?

No. The laws vary by state and depend on the nature of the crime. See the National Conference of State Legislature's publication on Convicted offenders required to submit DNA samples.

Do law enforcement agencies in the US have the ability take the DNA of all arrestees?

The court in Maryland v King ruled that law enforcement have the right to lawfully search an arrested person and to take his DNA sample. In practice, arrestees in many states do not routinely have their DNA sampled or it is only taken for certain specified crimes. See the National Conference of State Legislature's publication on DNA arrestee laws

What is familial searching? How is it different from investigative genetic genealogy?

Familial searching was pioneered in the UK and was first used in 2002. It is used in serious crime cases or in cold cases when there are few or no investigative leads. A search is made of a police DNA database to look for close matches to a DNA profile taken from a crime scene. Close relatives of an offender would be expected to share a significant proportion of an offender’s DNA profile and an offender could therefore be identified through their relatives. Police databases currently use between 17 and 24 autosomal STRs. Matches through familial searching can at best identify a potential sibling, parent, or child of the target. Familial searches are restricted to people who are already in the police database and who are therefore considered to have fewer privacy rights.

For background on familial search policies in the US see the 2015 report and webinars from the National Institute of Justice on Familial DNA Searching: Current Approaches.

Genetic genealogy tests use SNP microarrays which cover between 550,000 and 900,000 SNPs scattered across the genome. Using autosomal SNP data it is possible to identify matches with second, third and more distant cousins. Autosomal DNA databases consist of people who have not committed any crimes, not all of whom have proactively consented to law enforcement matching.

Which US states use familial searching?

Familial searching is not performed at the national level in the US.

According to the FBI website familial searching at the state level is being done in the following 10 states: Arkansas, California, Colorado, Florida, Michigan, Texas, Utah, Virginia, Wisconsin, and Wyoming.

Forensic Magazine reported in October 2017 that 11 states have used familial searching: Colorado, California, Florida, Michigan, Minnesota,Ohio, Pennsylvania, Texas, Utah, Virginia, Wisconsin, Wyoming. The list did not include Arkansas which is in the FBI list. Forensic Magazine suggested that Minnesota and Pennsylvania had discontinued use of the technique as of October 2017.

Familial searching was introduced in New York State in late 2017 though this use has been challenged in court.

Familial searching is forbidden by law in Maryland and Washington DC. Familial searching is not currently permitted in the NDIS (National DNA Index System) - the national CODIS database.


Is there a comprehensive list of links regarding cases solved through investigative genetic genealogy?

Not all of the cases where genetic genealogy was used have gone public so it is not possible to provide a comprehensive list. The criminologist Tracey Dowdeswell maintains an independent database of publicly announced solved cases which is updated on an annual basis. The dataset up to the end of October 2023 is available on Mendeley at The methods are described in a paper published in Forensic Science International Genetics Forensic genetic genealogy: A profile of cases solved (Volume 58, May 2022, 102679).

The Genealogy Explained website has taken Tracey Dowdeswell's dataset and converted the content into an accessible online searchable database.

The following websites also contain useful lists:

How many homicides are there each year in the US?

There were 17,284 reported cases of murder and non-negligent manslaughter cases in the 2017.

See the FBI reports on crime in the US.

How many murders are unsolved in the US?

In 2015 it was estimated that at least 200,000 murders since the 1960s remain unsolved.

Source: Kaste M. Why one third of murders in America go unresolved. NPR 30 March 2015.

How do these homicide rates compare with other countries?

Although the number of homicides has declined in the past twenty years, when viewed in international comparisons, the U.S. murder rate is still high compared to other industrialised countries. In 2012, Germany’s murder rate stood at 0.8 per 100,000 inhabitants, compared to 4.7 in the United States. See:

Further reading


See also


  1. Kennett D. Forensic Science International, Volume 299, June 2019, Pages 103-113.
  2. McDermott M. Investigative genetic genealogy: how does it work?. Genealogy Explained, 14 July 2020.
  3. Molteni, Megan (24 April 2019). "What the Golden State Killer tells us about forensic genetics". Wired. Archived from the original on 25 April 2019. Retrieved 25 April 2019. 
  4. Greytak, Ellen M.; Moore, CeCe; Armentrout, Steven L. (2019). "Genetic genealogy for cold case and active investigations". Forensic Science International 299: 103–113. doi:10.1016/j.forsciint.2019.03.039. 
  5. See the website of the Council for the Advancement of Forensic Genealogy
  6. "Ramage, Michael S. (2018). "Chapter 15: Forensic Specialization". in Shown Mills, Elizabeth. Professional Genealogy, Preparation, Practice & Standards. Genealogical Publishing Co.. p. 337. ISBN 9780806320724. 
  7. Petrone J. Forensic genomics market advances due to consumer databases, technology innovation. Genome Web, 9 January 2020.
  8. Murphy H. Why this scientist keeps receiving packages of serial killers' hair. New York Times, 16 September 2019.
  9. Detectives identify John Doe, victim of late 1980’s homicide. Press release from Snohomish Country, 12 August 2020.
  10. Legal Information Institute - Cornell Law School - Fourth Amendment