IGG in the trenches: Results of an in-depth interview study on the practice, politics, and future of investigative genetic genealogy

Abstract

Investigative genetic genealogy (IGG) is a new technique for identifying criminal suspects and unidentified deceased and living persons that has sparked controversy. In a criminal case, the technique involves uploading genetic information left by a putative perpetrator at the crime scene to one or more direct-to-consumer genetic genealogy databases with the intention of identifying the perpetrator’s genetic relatives and, eventually, locating the perpetrator on the family tree. In 2018, IGG helped to identify the Golden State Killer, and it has since been used in hundreds of investigations in the United States. Here, we report findings from in-depth interviews with 24 U.S.-based individuals involved in IGG that are relevant to the technique’s current practice and predicted future. Key findings include: an emphasis on restricting IGG as a conceptual and technical matter to lead generation; the rapid growth of a private and largely self-regulating industry to support IGG; general recognition of three categories of cases associated with distinct practical, ethical, and policy questions, as well as varying degrees of controversy; and the significant influence of perceived public opinion on IGG practice. The experiences and perspectives of individuals in the IGG trenches related to these and other issues are potentially useful inputs to ongoing efforts to regulate the technique.

1. Background

In 2018, investigative genetic genealogy (IGG) made headlines around the world when it was announced that the technique had been used to identify Joseph James DeAngelo as the Golden State Killer. [1] DeAngelo’s unmasking as the serial murderer and rapist who had terrorized California throughout the 1970s and 1980s was startling for two reasons. First, although law enforcement had devoted significant attention and resources to his capture, [2] DeAngelo had eluded the police for decades, and it had become increasingly unlikely that he would be identified and held accountable for his crimes during his lifetime. Second, DeAngelo was identified using an unusual investigative artifact: his family tree, which the investigative team constructed from information about his genetic relatives participating in direct-to-consumer (DTC) genetic genealogy databases populated by autosomal DNA profiles. This was one of the first times that the police had used the technique, now called IGG (among other terms; see Table 1), to solve a crime.

Table 1.

Terms and acronyms relevant to IGG.

Terms and acronyms	Meaning
short tandem repeat (STR)	Short, repeated sequence of DNA. The number of repeats varies from person to person. STRs are located in what are believed to be non-coding regions of the genome.
single nucleotide polymorphism (SNP)	Variant at a single position in DNA. The major direct-to-consumer genetic testing firms test between 576,000-683,000 autosomal SNPs.[3]
subject	Person whose identity is under investigation.
genetic genealogy	Use of genetic test results in combination with traditional genealogical sources to infer a person’s genetic relationships.
investigative genetic genealogy (IGG); forensic genetic genealogy (FGG); forensic investigative genetic genealogy (FIGG); forensic genetic genealogical DNA analysis and searching (FGGS); long-range familial searching	Deliberate process by which a direct-to-consumer genetic genealogy database compares a subject’s SNP profile to the SNP profiles of other genetic genealogy database participants, and law enforcement, and/or genetic genealogists working on their behalf, use the information generated by these comparisons, as well as information obtained from traditional genealogical and other sources, to develop the subject’s family tree and then to identify one or more leads for the subject from the family tree.
relative matching	Deliberate process by which a direct-to-consumer genetic genealogy database identifies a subject’s genetic relatives by comparing the subject’s SNP profile to the SNP profiles of other genetic genealogy database participants.
law enforcement matching	Relative matching conducted in the context of IGG.
GEDmatch; FamilyTreeDNA (FTDNA)	Direct-to-consumer genetic genealogy databases that are populated with the SNP profiles of database participants and provide relative-matching services to participants. Although their consent practices and policies are different, both GEDmatch and FTDNA permit IGG with respect to participants who are opted in to law enforcement matching.
forensic genetic database; law enforcement genetic database; Combined DNA Index System (CODIS)	Genetic database maintained by a governmental entity for law enforcement use that is populated with the STR profiles of persons convicted of and in some cases arrested for crimes, consistent with applicable laws and policies. CODIS is the generic term used to describe FBI-supported forensic genetic databases in the United States and the software used to run these databases.
partial matching	Deliberate or non-deliberate process by which a forensic genetic database identifies possible, close genetic relatives of a subject by comparing the subject’s STR profile to the STR profiles of individuals whose DNA is stored in the database using lower-stringency search criteria. Partial matching occurs during a routine search of the database.
familial searching	Deliberate process by which a forensic genetic database identifies possible, close genetic relatives of a subject by comparing the subject’s STR profile to the STR profiles of individuals whose DNA is stored in the database using specialized software designed for this purpose. Familial searching follows a routine search of the database.
Doe	Unidentified decedent or living person.
Jane Doe; John Doe	Unidentified decedent who is typically a teenager or adult. Some but not all Jane and John Does are homicide victims.
Baby Doe	Unidentified decedent who is a newborn or infant. Some but not all Baby Does are homicide victims.
living Doe	Unidentified living person. A living Doe might be unidentified because, for example, they are in a coma, have amnesia, or were kidnapped as an infant.
unidentified human remains (UHR)	Body or body parts of an unidentified decedent.
suspect	Person who is believed to be the perpetrator of a crime under investigation.
perpetrator	Person who committed a crime.
reference testing; third-party testing; target testing	Deliberate process of collecting and testing the DNA of a genetic relative of a subject to help narrow the scope of an investigation by law enforcement.

The steps of IGG are detailed in other publications. [4–7] Briefly, they are: (1) obtain DNA from the subject, or person whose identity is under investigation (e.g., a criminal perpetrator or unidentified decedent or living person (Doe); if the investigation is to identify a perpetrator, the DNA is collected from the crime scene or other location associated with the crime); (2) develop a profile of single-nucleotide polymorphisms (SNPs) from the DNA; (3) upload the SNP profile to a DTC genetic genealogy database that accepts such uploads from law enforcement (currently, the GEDmatch and FamilyTreeDNA (FTDNA) databases are the only commercial databases that accept such uploads); (4) build the subject’s family tree from the genetic relative matches generated by the database and using traditional genealogical and other sources, including public records; and (5) identify one or more leads for the subject on the family tree using relationship, case, and other information.¹

Importantly, the steps of IGG do not comprise the entirety of an investigation. [7] Rather, IGG is one of many techniques that law enforcement might use in the course of an investigation. When DNA is collected from a crime scene, according to best practices, [8–10] those other techniques will at least include developing a profile of short tandem repeats (STR) from the DNA. In the United States, that profile will then be uploaded to CODIS, a genetic database maintained by law enforcement that stores STR profiles of persons convicted of and in some cases arrested for criminal wrongdoing, to determine if it matches an STR profile stored in CODIS. [11] This search might encompass, or expand to include, partial matching or familial searching, which can help to identify possible, close relatives of the perpetrator whose profiles are in CODIS. [12]

If these techniques are not successful, law enforcement may turn to IGG to generate suspect leads. After one or more leads are identified from IGG, law enforcement will investigate those individuals before making an arrest. Again, according to best practices, [8,9,13] this investigation will at least include collecting a fresh DNA sample from any person identified as a suspect and generating a STR profile of that sample to determine if it is a direct match to the crime scene DNA.

According to one dataset, in the years since DeAngelo’s arrest, IGG has helped to clear over 1000 cases²—defined in the accompanying codebook as the identification of a Doe or criminal victim-offender pair—primarily in the United States. [14,15] This count emphasizes serial offenders because each of their crimes is counted as a separate case. At the same time, it excludes cases in which use of IGG has not been confirmed by any public agency as well as cases that were not publicized upon clearance and so did not appear in the researchers’ search results. [15] Thus, the actual number of cases cleared using IGG is likely larger.

As its use becomes more common, the novelty of IGG has begun to fade. However, public interest in its applications, with a focus on privacy implications, remains high. This interest has been fueled in part by periodic controversies regarding, among other things, changes in database terms of service, database security breaches, service of warrants on databases, and apparent violations of database terms of service. Some questions that these events have provoked include: Is the consent of DTC genetic genealogy database participants to law enforcement matching voluntary and fully informed? [16–19] What are the privacy expectations of database participants with respect to information they share for the purpose of discovering genetic relatives? Are those expectations reasonable? [20] Do individuals who choose not to participate in these databases have rights vis-à-vis genetic material they share with relatives who are, or are interested in becoming, database participants? If not, should they? [11,19] There also has been speculation about IGG’s potential use by other actors (e.g., insurance companies), in other kinds of genetic databases (e.g., clinical research databases), and for other purposes (e.g., to discriminate against individuals or groups or to conduct population surveillance).

To mitigate some of these concerns, U.S. federal and local authorities, as well as professional organizations and commercial entities, have developed policies and guidelines for IGG that place guardrails on its practice. [8–10,13] For example, the Interim Policy on Forensic Genetic Genealogical DNA Analysis and Searching developed by the U.S. Department of Justice (the DOJ Interim Policy): requires law enforcement to conduct a CODIS search before initiating IGG and to confirm the suspect’s identity before arresting them via direct STR comparison; prohibits law enforcement from using SNP profiles developed for IGG to determine a person’s health conditions or predispositions; and limits law enforcement collection of DNA from reference testers, or relatives of the subject who are not suspects but whose DNA is sought for testing to include or exclude branches of the family tree from further investigation. [8] However, the DOJ Interim Policy, like many other relevant policies and guidelines, is limited in its jurisdictional reach.

Meanwhile, several U.S. states have passed laws regulating IGG. In 2021, Maryland passed a comprehensive law that permits IGG for perpetrator identification in limited circumstances and subject to judicial approval. [21] The law also mandates licensure of laboratories and genetic genealogists involved in IGG and compliance with specific procedures related to reference testing, managing samples and information collected and generated during IGG, and reporting aggregate IGG case data. [21] That same year, Montana passed a brief law that prohibits law enforcement from obtaining familial DNA search results without a warrant. [22] More recently, Utah passed a comprehensive law that permits IGG, following law enforcement’s consultation with the prosecuting agency and state bureau of forensic sciences, for perpetrator, unidentified human remains, and other unidentified persons cases. [23]

Concurrent with the development of IGG policies, the IGG literature is growing and now includes rich accounts of its use in specific investigations, [24] as well as useful catalogues of aggregate and individual case data. [11,15] Surveys and interview studies have also been conducted with the public, genetic genealogy participants, database administrators, and other IGG professionals to probe IGG’s acceptability and to explore perceived benefits and ethical concerns. [20,25–28]

By comparison, few empirical investigations have been conducted to understand IGG’s technical practice or its predicted future, although this information is critical to effective policymaking for IGG. Those in the IGG trenches are important sources of this information because they know first-hand the capabilities and limits of the technique and the complexities associated with its application to different kinds of cases. They also have valuable experience with the use of IGG relative to other investigative techniques and in the context of complete investigations. Finally, they have their fingers on the pulse of how IGG has changed and is evolving, which can help to ensure that IGG policies remain effective over time.

In 2021, we conducted in-depth interviews with 24 U.S.-based individuals who conduct or facilitate IGG to understand their perspectives on and experiences with the technique. Here, we report interview data relevant to IGG’s applications, influences, and future, highlighting along the way areas of emerging consensus as well as continued controversy. These data are potentially relevant inputs to conversations about IGG taking place in classrooms, chat rooms, courtrooms, laboratories, and legislative chambers across the United States as well as in other jurisdictions where IGG is being practiced or is under consideration.

2. Methods

The study protocol was reviewed and approved by the Institutional Review Board of Baylor College of Medicine.

A purposive sample of interview candidates was identified based on a review of IGG-related media reports and the professional activities of the research team. A consultant to the project with subject matter expertise also recommended interview candidates but, to avoid conflicts, had no knowledge of who was invited or participated and was excluded from access to study instruments and data. Additional candidates were identified through snowball sampling.

To be considered for inclusion in the study, each candidate was required to: be at least 18 years old; be able to participate in an English-language interview; and have professional experience conducting or facilitating IGG as a genetic genealogist, forensic scientist, genetic genealogy business representative, member of law enforcement, or legal counsel. Because our research aims to inform U.S. policy, we are primarily interested in the practice of IGG in the United States, and so an additional inclusion criterion was that the candidate was a U.S. resident at the time of their interview. Candidates were sampled to promote demographic diversity and to capture a range of IGG experiences.

Each candidate was contacted by one author via email with an invitation that described the purpose of the study. If the candidate did not respond to the initial invitation within two weeks, a follow-up email was sent. No additional emails were sent after the second follow-up email.

Interviews were conducted from February 2021 to August 2021. Three authors conducted interviews using a semi-structured interview guide that included questions about individual caseload, IGG practice and developments, and ethical and policy issues. An abbreviated interview guide is provided in the Supplemental File. All interviewees were interviewed as individuals. None purported to speak on behalf of their employers, affiliated institutions, or colleagues. All interviews were conducted via video conference and audio recorded with permission. Each interviewee was asked to verbally consent at the start of the interview and was offered a US$100 gift card at the end of the interview.

Audio recordings of interviews were professionally transcribed, and each transcript was deidentified and reviewed for transcription errors by two authors. Deidentified, corrected transcripts were then uploaded into the qualitative software Dedoose (Los Angeles, CA: SocioCultural Research Consultants, LLC) for data management and storage. Field notes summarizing information learned and/or documenting impressions of and reflections on individual interviews were stored in secure project folders.

Transcripts were coded using a codebook and analyzed according to thematic analysis using both deductive and inductive approaches. [29,30] Additional details about our development and use of the codebook and analytical processes are provided in the Supplemental File. Based on consideration of the coding reports, data summaries, and field notes, the study team identified salient themes.

3. Results

Each interview lasted between 59 and 156 minutes. The median length was 83 minutes.³

The remainder of the results are presented as interviewee characteristics and experiences followed by four themes: IGG as tip generation; expansion and specialization of IGG expertise and services; categories of IGG applications; and controversies, best practices, and practice influences. Quoted information is attributed to interviewees using their assigned study ID.

3.1. Interviewee characteristics and experiences

3.1.1. Demographics

Twenty-nine individuals were invited to participate in an interview, and 24 completed an interview, for a response rate of 83%. Of the five who did not participate in an interview, two did not respond to email invitations and three declined to schedule an interview for scheduling reasons or due to concerns about obtaining institutional permission to participate.

The median age of interviewees was 47 years old. Exactly half of all interviewees were female (n = 12, 50%), most identified as White (n = 21, 88%), and most were located in the U.S. South (n = 10, 42%) or U.S. West (n = 9, 38%) (Table 2). Interviewees represented a broad range of experiences relevant to the practice of IGG, as indicated by their classification by primary role vis-à-vis IGG as: genetic genealogist (n = 7, 29%), forensic scientist (n = 5, 21%); genetic genealogy business representative (n = 3, 13%); member of law enforcement (n = 7, 29%); or legal counsel (n = 2, 8%).

Table 2.

Interviewee characteristics (N = 24).

Characteristic	n (%)a
Age, in years
< 39	4 (17)
40-49	10 (42)
> 50	6 (25)
Unknown/unconfirmed	4 (17)
Gender
Female	12 (50)
Male	9 (38)
Gender non-conforming or unknown/unconfirmed	3 (13)
Race/ethnicity
White	21 (88)
Non-White or unknown/unconfirmed	3 (13)
Geographic locationb
U.S. Northeast	1 (4)
U.S. Midwest	2 (8)
U.S. South	10 (42)
U.S. West	9 (38)
Unknown/unconfirmed	2 (8)
Primary rolec
Law enforcement	7 (29)
Genetic genealogist	7 (29)
Forensic scientist	5 (21)
Genetic genealogy business representative	3 (13)
Legal counsel	2 (8)

^aSum of percentages may not equal 100% due to rounding.

^bAs defined by the U.S. Census Bureau.

^cClassifications made by the research team based on their understanding of the interviewee’s primary role vis-à-vis IGG.

For the remainder of this section 3.1, business representatives were excluded from analysis because they were not directly involved in specific investigations; therefore, percentages are calculated based on N = 21.

3.1.2. IGG caseload

Interviewees described a range of experiences with IGG and included, on one end of the spectrum, pioneers of the technique, and on the other end, individuals who had more recently begun to use or facilitate its use in investigations. Three-quarters of interviewees (n = 16, 76%) stated that they have been involved in at least six cases using IGG (Table 3). Approximately one third (n = 6, 29%) described involvement in over 50 cases.

Table 3.

Interviewee IGG caseload (N = 21)^a.

	n (%)b
Total number of cases involving IGG
1-5	5 (24)
6-10	2 (10)
11-20	5 (24)
21-50	3 (14)
> 50	6 (29)
Kinds of cases in IGG caseloadc
Perpetrator cases	18 (86)
Doe cases	17 (81)
Baby Doe casesd	7 (33)
Proportion of perpetrator cases in IGG caseload
0-25%	4 (19)
26-50%	4 (19)
51-75%	3 (14)
76-100%	10 (48)

Perpetrator cases=investigations of unidentified criminal perpetrators; Doe cases=investigations of unidentified deceased or living persons, including human remains; Baby Doe cases=investigations of unidentified deceased newborns or infants.

^aN excludes genetic genealogy business representatives.

^bSum of percentages may not equal 100% due to rounding.

^cNot mutually exclusive.

^dDue to how this question was asked during interviews, Baby Doe cases are reported in this table as a subtype of Doe cases.

Interviewees reported involvement in different kinds of cases. Almost all (n = 18, 86%) were involved in at least one case using IGG to identify a criminal perpetrator. Almost half (n = 10, 48%) reported that a significant majority or all (76%–100%) of their IGG caseload consisted of perpetrator cases, while four interviewees (19%) reported that perpetrator cases comprised 25% or less of their IGG caseload. All interviewees participating in perpetrator cases reported that the cases concerned violent crimes.

Most interviewees (n = 17, 81%) had been involved in at least one case using IGG to identify deceased or living Does. Two only worked these cases and were not also involved in perpetrator cases. Finally, seven interviewees (33%) were involved in at least one case using IGG to identify deceased newborns or infants (Baby Does).

3.1.3. IGG activities

Interviewees reported involvement in multiple activities relevant to IGG. Most (n = 15, 71%) were involved in at least 3 of the 11 activities that we tracked (Fig. 1A). None were involved in more than 7 activities.

Fig. 1.

A. Interviewee participation in IGG-relevant activities, by total number (N = 21); B. Interviewee participation in IGG-relevant activities, by activity (N = 21).

With respect to specific activities (Fig. 1B), notably, most interviewees (n = 16, 76%) reported at least involvement in the development of family trees and lead identification. This group included interviewees who we classified in a primary role other than genetic genealogist. Seven participants (33%) supported their organization’s development of IGG programs, procedures, or policies, and six (29%) participated in IGG training or the development of educational materials for individuals outside of their organizations.

3.2. IGG is a powerful tool for tip generation

IGG was repeatedly described as a powerful tool that, although still relatively new, is changing the nature of investigations involving DNA evidence. Reflecting this confidence and enthusiasm, one law enforcement officer remarked: “I truly believe that this is the new fingerprint.” (14) Another concurred that IGG “is the most powerful tool that I’ve seen come along in the [decades] that I’ve been in law enforcement.” (19) It has resulted in solving especially tricky cases that investigators said could not be solved any other way. Focusing on perpetrator cases, a genetic genealogist explained, “in case after case, the comment is, ‘That person was never on our radar.’” (5)

Still, many emphasized an important check on current IGG practice: it generates leads, or “hot tips,” of a person’s identity, not confirmatory evidence of it. (5) A business representative described their job as providing detectives a “starting point,” or an “arrow,” that should be interpreted as, “Hey start here. Here’s the direction [to] work in to find out who the perpetrator is.” (2) The leads are then investigated, and the identity of the subject is confirmed via direct STR comparison between the crime scene DNA and a fresh DNA sample collected from the suspect. Thus, explained an interviewee, genetic genealogy can ”point[] you in the right direction,” but when the case is solved, “[g]enetic genealogy didn’t solve it. When I collected DNA from a suspect that I identified through genealogy, the state lab solved it by making that comparison and telling me, ‘Hey, that’s him.’” (12)

Interviewees described three implications of restricting IGG’s role in an investigation, conceptually and technically, to lead generation. The first is that, according to many interviewees, the genetic genealogy work, and the names of genetic relative matches in particular, are not evidence in the case against an alleged perpetrator and therefore need not be detailed in affidavits or presented in the courtroom. A genetic genealogist elaborated:

[That work] should be treated as being an investigative tool. It should not be something that goes to court. At least in [state], I should never be asked to testify in court, because that’s not how we’re identifying people. [The direct match] is the evidence that’s used for actually getting an arrest warrant and a search warrant. It’s not what I did. (5)

Similarly, one interviewee endorsed “keep[ing] the genealogy out of your affidavit” because “the guilt or innocence of the suspect, it really has nothing to do with the genealogy whatsoever .… What matters, what’s compelling, is I have a one-to-one comparison of the suspect’s DNA and the crime scene DNA.” (15)

The second implication of restricting IGG’s role to lead generation, according to some interviewees, is that IGG should not result in wrongful arrests or convictions. As long as leads are investigated and there is independent, genetic confirmation of identity, they explained, the stakes of this work should be low: “[T]he good thing is, you can’t really make a mistake here. If we follow the policy [requiring STR comparison testing], we cannot arrest the wrong person. It’s impossible to do it.” (14)

Third, some connected this point to the debate about mandatory licensure of investigative genetic genealogists, as provided in the Maryland law. [21] Specifically, they opposed mandatory licensure on grounds that it will create new burdens but insufficient offsetting civil liberty benefits. “Why would it matter if you have a certified genealogist or not, if you’re not going to arrest anybody before you have STR confirmation?”, one interviewee asked. (15) “[O]nce you get to the right place, it doesn’t really matter how you got there.” (15) Although not directly stated, it was implied that the activities leading to the arrest are lawful.

3.3. IGG expertise and commercial opportunities are expanding

Mandatory licensure proposals have been one response to the rapid growth of a commercial industry to support IGG. This industry is comprised of: laboratory scientists and bioinformaticians who develop SNP profiles; commercial genetic genealogy databases that identify relative matches of subjects from uploaded SNP profiles; and genetic genealogists who help identify leads from genetic relationships and other information for further investigation.

Interviewees explained that the IGG industry is largely self-regulating, and for genetic genealogists in particular, there are few barriers to entry given that the work does not require specific credentials or access to expensive resources. One interviewee explained that these permissive conditions have encouraged an influx of individuals “hanging a shingle out, like, ‘I do it—IGG. I do IGG.’” (6) Some genetic genealogists have initiated casework by, for example, finding Does on websites such as Find-A-Grave and then contacting law enforcement with offers to help identify the Does, sometimes for free. Typically, however, law enforcement selected genetic genealogy and laboratory partners based on positive personal experiences working with them or the recommendations of peers who vouched for the quality and integrity of their practices. Law enforcement interviewees also described conversations in which they were counseled not to work with specific vendors—sometimes based on rumors and possible misinformation fueled in part by what one interviewee described as “cutthroat” competition for cases. (23) Indeed, five interviewees commented that competition was driving some industry actors to make questionable claims about their capabilities or achievements. Summarizing the industry, one genetic genealogist called it “the Wild, Wild West.” (11)

At the same time, demand for services and competition have promoted technical innovation. While some genetic genealogists described new strategies for developing family trees from fewer and more distant relative matches, interviewees largely focused on scientific advances in DNA extraction, sequencing, and restoration using increasingly small, degraded, and contaminated samples. Several interviewees noted that, only a few years ago, at least 20 nanograms of DNA was required to develop a usable SNP profile for database upload, but now cases are being solved using less than one nanogram. Although technical barriers remain, “it’s amazing how quickly that technology has evolved,” one interviewee remarked. (5) Techniques for extracting and analyzing DNA from rootless hair were also noted developments that have expanded the kinds of specimens eligible for IGG. Some described optimism that the technology will improve even further. For example, one laboratory advised an interviewee not to give up on an old DNA sample after concluding that it could not yield a usable SNP profile: “They claim in five years technology will have skyrocketed and maybe we could try it again.” (12)

Some believed that law enforcement is unlikely to soon acquire the expensive specialty equipment required to develop usable SNP profiles and therefore will continue to outsource this work to commercial laboratories for some time. By contrast, several described how genetic genealogy is already being conducted inside some agencies. Law enforcement interviewees explained that this makes sense from a role perspective given the “crossover between genealogy and law enforcement”: “[B]asically [IGG] is research. That’s all it is. And many law enforcement analysts or detectives, that is our wheelhouse: research, investigating, putting pieces of a puzzle together.” (8) Moreover, for cases involving family trees that are especially difficult to construct because there are few close relative matches or they involve, for example, misattributed parentage, unrecorded adoption, or endogamy, in-house genetic genealogy could be more cost-effective than outsourcing to an independent genetic genealogist, depending on their fee structure:

A lot of the really difficult cases can take months and months and months. … The cost to do that is just prohibitive if you’re outsourcing. But if you’re doing it in-house, you can work on it, you might have to put it away for a while, [but you] come back to it. (7)

Still, predictions were mixed as to whether in-house genetic genealogy will become the norm. Some questioned whether agencies can afford to train and retain the necessary personnel given that “when you get into something very technical … and it’s in hot demand, they can go just about anywhere and make more money” after their retention contract has expired. (3) Most, however, saw a future in which, particularly at the state level, agencies include dedicated IGG personnel capable of performing the genetic genealogy work themselves but with the budgets to outsource as needed.

3.4. Different objectives, practical issues, and ethical and policy questions are associated with three IGG applications

Turning to applications of IGG, interviewees described unique objectives, practical issues, and ethical and policy questions associated with three categories of cases: perpetrator cases, John/Jane Doe cases, and Baby Doe cases.

3.4.1. Perpetrator cases

According to interviewees, the main objectives of IGG in perpetrator cases are to bring closure to victims and their loved ones and to ensure that perpetrators are held accountable for their crimes. Further, several interviewees focused specifically on using IGG to ensure that the right person is held accountable. “I think if you’re playing fantasy policeman,” explained a member of law enforcement, “if you get one fantasy point for an arrest or two fantasy points for a drug seizure, I think you get a hundred fantasy points if you can free someone from jail that shouldn’t be there.” (14) For these interviewees, the most compelling and rewarding uses of IGG are to prevent wrongful arrests and to exonerate the wrongfully convicted.

Interviewees explained that IGG is primarily being used to help solve cold cases—especially those that investigators have become emotionally invested in over the years and have a goal of solving before their retirement. Indeed, one described IGG as on its way to becoming “the standard [tool] for cold cases.” (21) However, some were also beginning to use IGG in active cases and there was broad support for this application. First, interviewees explained, IGG can save on the total costs of an investigation by shortening it. Second, by identifying offenders earlier in an investigation, IGG can prevent their commission of additional crimes. One interviewee explained IGG’s potential “to remove the word ‘serial’ from serial rapist or serial killer… they do it once, and we can catch them.” (6) Moreover, with respect to violent offenders who abuse members of their household, identifying them via IGG can translate into “one less person to victimize their family and those people close to them, even if they never attack[] another stranger.” (1) Third, it was noted that using IGG in active cases can help to narrow the number of individuals who ultimately are investigated for a crime and in this way can be privacy protective: “[T]he sooner this is used, the less innocent people have to be investigated from the beginning. And that’s really the power of this tool.” (1) For these reasons, several endorsed integrating IGG into the standard workflow of cases so that it becomes available for use soon after an unsuccessful CODIS search.

By contrast, there was general consensus that IGG should not be applied to non-violent crimes at this time. As noted above, no interviewee reported using or facilitating IGG to investigate non-violent crimes, consistent with the DOJ Interim Policy and GEDmatch and FTDNA terms of service. [8,31,32] Some supported this exclusion on grounds that using IGG to investigate such crimes is not an appropriate use of limited resources. Others felt that the exclusion strikes the right balance between competing ethical priorities:

You’ve got the public safety side and you’ve got the public privacy side of things. You can’t have one or the other, right? … “We’re going to go all private, fine.” Then you’re not going to solve those cases. Or you can go the other way and go, “Well, we’re going to be all about public safety,” which means you trample over your privacy rights. There’s got to be a degree of proportionality to me in that. And when you talk about what’s that proportionality look like, to me, safety is you have the right to not get murdered or raped. I do not and would not support genealogy being used for property crime, for example. I would not support that. (22)

But the most frequently cited reason for supporting the exclusion was public opinion. One interviewee elaborated: “[B]ecause I care about the overall survival of the genetic genealogy industry and investigative genetic genealogy as a tool for good, I think it’s wise to limit it to the most serious crimes.” (1) Citing research, another concurred:

The public perception on most of these things is very pro doing this as long as it [is] for a violent crime. We really basically live and die off this, by the public being in support of this. So, we want to follow what the public wants. (7)

A minority of interviewees, however, questioned whether all non-violent crimes should categorically be excluded from IGG. One believed there should be “a door left open for potential exceptions” to account for unusual case circumstances (10), and two indicated that these exceptions might include, specifically, serial burglary. This was justified as follows:

[A] lot of serial burglars ended up in a situation where sooner or later they killed somebody that’s living in the home. So if you have a serial burglar, it’s probably a good tool to catch him, to prevent him from committing a murder someday. (19)

Citing the Golden State Killer, who began his criminal career as a burglar, another asked: “So yeah, do you want to start out maybe going after burglars, because you don’t want them to become rapists?” (5) However, this interviewee stopped short of endorsing IGG to identify non-violent criminals at this time and supported empirical research to help identify those who are likely to graduate to violent offenses.

3.4.2. Jane/John Doe cases

Considering Doe cases, interviewees noted that they share with perpetrator cases the objective of closure, although the mystery that is solved is not who harmed a loved one but what happened to them following their disappearance. Use of IGG to identify deceased Does helps to “get [them] back to their families” for burial and mourning. (23) “Until they have a name again, we are their voices, and we are their families,” explained a genetic genealogist. (23) Although some Doe cases double as perpetrator cases when the deceased was the victim of a crime, others do not involve criminal circumstances; death may have resulted, for example, from exposure, accident, or suicide. To one interviewee, use of IGG in this subgroup of cases involving deceased older children and adults (Jane/John Does) is analogous to adoptees seeking to identify their biological parents using genetic genealogy: “[T]he use case for unidentified human remains is no different from the use case [for] an adoptee looking for their biological parents. Everybody’s looking for closure here. It’s not a criminal case.” (22)

Jane/John Doe cases were identified as the least controversial application of IGG, with “huge support, tremendous support, pretty much across the board.” (1) Indeed, some opined that public acceptability is why GEDmatch changed its terms of service in January 2021 to allow law enforcement use of its entire database, with no provision for individual opt outs, when the purpose is to identify a Doe. [33] This change had the effect of “dramatically” increasing the number of genetic relative matches to Does provided by the database, (20) making these cases now easier to solve than perpetrator cases. Finally, one interviewee remarked on the relative value of using IGG to identify unidentified human remains in mass graves and conflict zones:

This is where we see the real power of genetic genealogy. Yes, you get the headline of violent crime, … but actually we see a much broader application of this beyond violent crime to unidentified human remains because that’s the key. That’s the hidden epidemic in the world. (22)

3.4.3. Baby Doe cases

Importantly, many interviewees recognized a moral distinction between Jane/John Doe cases and Baby Doe cases, even if they did not agree that the distinction was justified. Unlike Jane/John Doe cases, Baby Doe cases were described as highly controversial. Further, whereas controversy surrounding perpetrator cases concerned when and how to use IGG, controversy surrounding Baby Doe cases concerned whether to use IGG at all.

On one side of this debate, an interviewee explained, are those who oppose the use of IGG to identify Baby Does due to concerns about the prosecution of women who may have become pregnant and given birth in “desperate” situations that involved poverty, abuse, or mental illness. (1) Although the interviewee believed that these circumstances represent the minority of Baby Doe cases “in reality, that’s not how people perceive it.” (1) Fueled by these perceptions, according to a genetic genealogist, those who work Baby Doe cases are being “scolded” and “attack[ed]” in online forums. (16) Indeed, some cited fear of backlash, rather than personal qualms, as the reason why they declined to work Baby Doe cases:

A, because we need public support, and B, because if people didn’t [support IGG], they’d start pulling their kits out [of the databases]. We do not want that applecart turned over .… That was the reason [I declined to work these cases], not because I don’t feel justice shouldn’t be done for baby cases. (11)

Others expressed concern about misidentification of stillborn deaths as homicides and did not want to be involved in the “potential villainization” of these mothers. (9)

While recognizing that Baby Doe cases are generally treated as a special category of Doe investigations, some interviewees did not believe this distinction is justified. “A deceased baby that died as a result of being left—in my mind, that’s a human being,” explained an analyst, “and there’s absolutely no difference between an infant, a newborn, and an adult.” (17) In all cases, the objective is the same: to name them. Even when the baby was not given a name by their parents, argued some interviewees, it is a matter of human dignity to provide them an identity because doing so recognizes and honors their existence in the world.

Finally, several interviewees rejected consequentialist arguments for special treatment of Baby Doe cases on grounds that these arguments conflate the steps of identification of a Baby Doe with law enforcement’s later investigation of their death and, when ruled a homicide, prosecutors’ efforts to hold someone accountable for it. But, they argued, these are distinct steps. Summarized a genetic genealogist: “My job is to identify the infant. I do not play judge and jury. Whether or not they prosecute is not on my shoulders.” (16) When these roles are conflated, another interviewee cautioned, a different kind of injustice could result:

I don’t think we want to live in a world where law enforcement gets to pick and choose what cases, what laws they enforce and what laws they don’t. … So you have to apply that to the abandoned babies too. (3)

3.5. Controversies persist, but best practices, shaped by perceived public opinion, are emerging

Beyond specific IGG applications, interviewees debated two issues. The first was mandatory licensure of genetic genealogists. As mentioned above, some dismissed mandatory licensure as “a solution looking for a problem.” (14) However, others viewed mandatory licensure as essential for the establishment of minimum standards and best practices related to protection of case information and efficient and accurate tree building, which helps to shorten the time and narrow the scope of an investigation. For example:

[I]f a genealogist is working on a case, and they come to a point, I mean, a branch in the family tree, and they’re like, “You know what? You need to go target test these 18 people”—I think that is worrisome. I think genealogists should be able to narrow it down a little bit more than that. If they’re telling these law enforcement agencies to go out and talk to these 18 people, I think that’s honestly sloppy genealogy. And they should be giving law enforcement agencies more targeted leads, because you can. (6)

Several interviewees did not oppose licensure in theory but questioned how competence would be evaluated and who would be in charge of developing standards. Relatedly, one interviewee worried about the proliferation of state licensure programs, each with its own requirements and standards, because this could impose significant burdens on independent genetic genealogists whose work falls under the jurisdiction of multiple states.

But the most contentious issue was the practice of uploading subject DNA to genetic genealogy databases in violation of their terms of service. This practice covers two activities: (1) uploading subject DNA to databases, such as MyHeritage, that prohibit law enforcement participation for any reason, and (2) uploading subject DNA to databases, such as FTDNA, that permit law enforcement participation under specific conditions that are not met in a particular case. Four interviewees described personal knowledge of these activities, especially in the early days of IGG, although two mentioned recent incidents. A number of interviewees strongly opposed this practice; one described banding with others in the spirit of a “neighborhood watch” to report suspected policy violations to databases. (16) Reasons for concern about this practice included both personal belief that it is unethical and worry that it could be IGG’s undoing:

I’m very concerned about the use of databases against their terms of service. … I think that is ethically wrong, but I also think it’s extremely dangerous for the survival and future of investigative genetic genealogy. Public perception could be influenced in a very negative way. (1)

Two interviewees looked to the development of DTC genetic databases that exist solely for law enforcement purposes as a way to possibly help reduce instances of prohibited use. If terms of service make explicit the purpose of these databases and do not allow any participant to refuse consent to law enforcement matching, it would not be possible for law enforcement to violate these terms of service. Further, databases populated by the DNA of volunteers whose only interest is to help solve crimes might take special interest in a proposal, mentioned by two interviewees, that would allow them to claim reward money as crime tipsters: “[T]hey are doing a huge service to the public and that should be recognized more than it is,” argued one interviewee. (1) “And if that reward money is just sitting there, why not? They were the lead that led to the arrest, so it seems like that should qualify” for cash rewards for information from groups like Crime Stoppers. (1)

However, some did not object to the practice of uploading against terms of service, even if they did not do so themselves, for two reasons. The logic for the first reason was as follows: DTC genetic genealogy databases are online social platforms, online social platforms are public spaces, and it is not illegal or unethical for law enforcement to conduct investigations by participating in public spaces. The second reason was based on the argument that it might be unethical for law enforcement not to do everything they are legally allowed to do to fulfill their professional responsibilities to protect the public and solve crime. In the case of a child victim, an interviewee argued, “I want you to put yourself in those parents’ shoes and just say, what is your expectation of law enforcement? Follow the rules that don’t really exist [about terms of service] that we’ve made up?” (14) These interviewees did not appear concerned about public backlash given, for example, seeming acceptability of participation in Facebook against terms of service:

Facebook says you can’t pretend to be somebody not on Facebook. Should law enforcement not do that? Should I not contact that guy? And try to figure out where your kidnapped daughter is so that we can rescue her? Of course, any rational person would say that’s fine to do. (15)

Despite these continued controversies, interviewees explained that best practices for IGG are emerging as experience with the technique expands and lessons learned accumulate and are disseminated. Thus, as discussed above, there was consensus among interviewees on the conceptual and technical restriction of IGG to lead generation and the related practices of conducting confirmatory genetic testing before arresting a suspect, as well as keeping confidential the names of genetic relatives identified from IGG. Interviewees also converged on procedures for reference testing of genetic relatives that included: requesting a DNA sample, or requesting individuals who have already tested to opt in to law enforcement matching with their existing SNP profile, based on disclosure of truthful information; obtaining consent in writing and/or via audio recording; and if the request is declined, moving on to another relative. In addition, interviewees described a common strategy of conducting reference testing only with distant relatives based on experience that they are more likely than close relatives to agree to the request and also less likely to know and therefore tip off the suspect.

Finally, interviewees identified key influences on IGG practice and its future. Many noted general adherence to the DOJ Interim Policy, even among those, such as state and local detectives whose IGG activities are not funded by the DOJ, who are not required to follow it. Summarized one interviewee, “I do think that [the DOJ Interim Policy] has reached a lot of people, and it has been very successful in establishing a framework for how this is done, at least from the law enforcement side.” (6) Another concurred: “[J]ust about everybody I know [is] following the DOJ guidelines.” (22) An additional influence on practice was the desire to avoid missteps that might jeopardize cases at trial. Law enforcement is “thinking ahead to the courtroom,” explained one interviewee, and does not want to give judges reason to exclude critical evidence. (11)

However, the most frequently cited practice influence, by far, was public opinion. Several explained that this is because IGG depends for its existence on public support. “[W]e live and die by public opinion,” one member of law enforcement explained. (7) “And if we don’t have public opinion on our side, then our ability to use IGG is going to be greatly hindered” when database participants opt out of law enforcement matching or remove their profiles altogether from the databases. (7) In this way, public opinion acts as “a feedback mechanism on the police” as follows: “[I]f they act like cowboys, they’ll get reactionary legislation that will shut [IGG] down. And then that doesn’t serve anybody’s purpose. So I think they’re cognizant of it, they’re very cognizant of it.” (22)

But one interviewee explained how efforts to “protect” the technique from negative attention can be in tension with its appropriate utilization:

[O]ur two main goals [are] number one, to solve cases, but number two, to protect the technique. And those two goals are equally as important. Because if we’re solving cases, but not protecting the technique, then that’s a failure, because the technique is going to go away and we’re not going to be able to use it. But if we’re so protective of the technique that we’re not solving cases, then that’s a failure too. … You need to be able to do both. (15)

Moreover, a strategy that relies on public support for IGG’s “protection” can be frustrated by public misunderstanding of IGG, which some interviewees viewed as widespread. Indeed, nine interviewees described a “huge misconception” about IGG: the belief that, when they participate in GEDmatch and FTDNA, investigators “get people’s DNA”—meaning the complete DNA profiles of database participants identified by the database as genetic relatives of the person under investigation. (8) Two interviewees faulted the media for promoting this misconception and/or others, whether unintentionally by using ambiguous language or intentionally via “fear mongering.” (16)

Finally, some interviewees expressed frustration about what they perceived as under-appreciation of IGG’s benefits. One benefit that they wished was more widely understood is that IGG can reduce the number of individuals pursued as suspects:

Investigative genetic genealogy—and people need to understand this—has hugely narrowed the suspect pool of people who are being watched, surveilled, investigated, annoyed, or have consequences when detectives come knocking at their door and hauling them in. … And now instead of 100 people, [law enforcement] can narrow it down to four people they follow. (11)

Others emphasized IGG’s role in solving crimes that were not solved, and might not ever have been solved, any other way. The emotional and psychological benefits of case resolution for victims and their families are something that “I think a lot of people don’t see,” explained one interviewee. (15) “[T]hey may or may not know it,” elaborated another, but:

This is a way for regular citizens to become superheroes. … [T]hey are making a difference in a lot of these cases. … They are providing closure to the victims and victims’ families. And I think that’s the message that needs to get out to the public. (10)

4. Discussion

To our knowledge, this is one of the first in-depth studies to collect data relevant to experiences with IGG and predictions of its future from practitioners and others who facilitate the technique. Key findings include: an emphasis on restricting IGG as a conceptual and technical matter to lead generation; the rapid growth of a private and largely self-regulating industry to support IGG; general recognition of three categories of cases associated with distinct practical, ethical, and policy questions, as well as varying degrees of controversy; and the significant influence of perceived public opinion on IGG practice.

IGG has been called a “game changing,” “revolutionary” advance in human identification, [34] and this assessment aligns with our interviewees’ in-the-trenches experiences with the technique. However, interviewees were careful to distinguish the direct outputs of IGG from its power and utility. Specifically, those outputs were consistently described in modest terms as only leads. Many interviewees emphasized that this framing is important from an ethical and legal perspective because leads are merely tips that point an investigation in one or more directions. They are not evidence that serve as the basis for arrest or conviction. Therefore, according to interviewees, IGG activities do not need to be detailed in court documents. This practice of omission is reportedly consistent with FBI practice, although it is increasingly coming under fire for potentially hiding investigative missteps or unethical practices. [35,36] What information about IGG activities can and should be shared during criminal proceedings, with whom, and when, are questions with important implications for the practice of IGG that should be examined in future research.

Separately, the practice of omission has been criticized as “offensive” to the public who, it has been argued, “deserve[] to know” when IGG is used given that the technique relies on members of the public to participate in genetic genealogy databases and opt in to law enforcement matching. [35] One way to address this criticism is by offering to privately inform database participants when they are identified as a genetic relative of a subject upon case resolution. DNA Justice, a nonprofit genetic database that exists solely to assist law enforcement in investigations of violent crimes and unidentified human remains, is the only database that currently follows this practice. [37] Interestingly, this practice could serve a secondary purpose of helping participants claim rewards offered to crime tipsters. Under current eligibility rules, it does not appear that identification as a relative from IGG by itself qualifies for tip rewards. But at least one relative has stated that she wished she had been eligible for the $10,000 reward offered by the family of the victim whose case her DNA had helped solve, [38] and some of our interviewees supported revisiting eligibility rules to allow such claims. We find this idea intriguing, although it merits careful analysis that is beyond the scope of this article.

More broadly, a few interviewees noted that databases of SNP profiles contributed by members of the public exclusively for investigative purposes could help address concerns related to consent and law enforcement participation against terms of service. At least two such databases already exist: in addition to DNA Justice, Othram, a for-profit business, maintains a database known as DNASolves. [39] The DNA Justice database is growing but remains small⁴; the size of DNASolves is not known but is also likely small given that, like DNA Justice, it is not associated with genetic relative-finder or other self-discovery services. Unless these databases experience rapid, substantial growth, the outlook for integrating them into the standard IGG workflow, as well as helping to reduce instances of participation against terms of service in commercial databases, remains dim.

Many interviewees contrasted leads generated during IGG with evidence establishing a subject’s identity. In perpetrator cases, this evidence usually will include a direct match between the STR profile of the suspect’s DNA, obtained from a fresh sample, to the STR profile of crime scene DNA. It is possible, however, that the quantity or quality of crime scene DNA may be insufficient to develop both a SNP profile and a STR profile. [6] None of our interviewees discussed the possibility of an arrest based on an investigation involving IGG but not supported by a direct match of STR profiles—although perhaps supported by a direct match of SNP profiles. These possibilities might not have been widely appreciated at the time of the interviews, although they are beginning to be confronted, including in provisions of the Utah law that generally require confirmatory genetic testing prior to arresting and charging suspects in cases involving IGG but do not specify the kind of genetic testing and also allow for exceptions. [23] This is a developing area that merits attention.

Interviewees’ discussion of three categories of IGG cases included several important insights. First, applications vary with respect to their concerns and perceived benefits, where John/Jane Doe cases were generally recognized as the least controversial of all possible uses of IGG and Baby Doe cases as the most controversial. This finding suggests that it would be a mistake for policymakers to automatically lump all IGG applications together and treat them the same for all purposes. Some IGG policies treat perpetrator and Doe cases the same; others do not, including GEDmatch’s policy to opt in all participants to law enforcement matching for Doe cases but not perpetrator cases. [31] Notably, policies that do distinguish between perpetrator and Doe cases often do not distinguish Baby Doe from Jane/John Doe cases, consistent with the position of several interviewees. Nevertheless, given continued controversy surrounding the use of IGG in Baby Doe cases, [40] it would be prudent to consider whether any policy differences are warranted, although such discussions should not ignore the broader legal context in which Baby Doe cases are handled by the U.S. criminal justice system.

Several interviewees expressed enthusiasm for the use of IGG to exonerate individuals wrongly convicted of crimes. To date, however, IGG has directly helped to exonerate only two individuals convicted of violent crimes. [14,15] Maryland and Utah have passed laws that explicitly permit IGG by post-conviction counsel, subject to guardrails. [21,23] Other policies, however, do not address this application, raising the question whether its possibilities are well known to policymakers. Given strong public interest in exonerating innocent persons, who are estimated to account for 4%–12% of felony convictions, depending on the populations and cases under study, [41–43] additional research is needed to understand stakeholder perspectives on, and practical, legal, and ethical issues relevant to, defense uses of IGG.

There is ongoing debate about where IGG should be positioned in the investigative workflow. Some commentators have indicated comfort with its use only after all traditional investigative techniques have been exhausted, some amount of time has elapsed, and the case has gone cold. [44] However, as more years-old and decades-old cases were cleared using IGG, it was inevitable that law enforcement would begin using it in active investigations, [11] especially where the perpetrator was believed to present a serious, ongoing threat to public safety. In a recent, high-profile example, IGG was used to help zero in on Bryan Kohberger as the alleged murderer of four Idaho college students only weeks after the crimes were committed. [35] Several interviewees supported use of IGG in active perpetrator cases and made compelling safety and resource arguments as to why IGG should not be restricted to cold cases—and perhaps active cases should take priority over cold cases, especially those committed many decades ago by perpetrators who are now likely deceased.

Many interviewees remarked on the rapid growth of a private industry to support IGG. Although they marveled at the scientific advances in specimen analysis that this industry already has achieved, some worried about the rush of independent genetic genealogists, representing varying degrees of competence, to offer their services to law enforcement. Yet, interviewees did not agree on whether the potential harms of low-quality genetic genealogy justify practitioner licensing requirements. Notably, these discussions focused on competence, although licensing regimes can also promote ethical conduct. Thus far, Maryland is the only U.S. state to mandate licensure of genetic genealogists who assist with IGG. [21] Although the deadline for establishment of this program is not until October 2024, a task force charged with implementing the new regulations was suspended due to lack of resources and the fate of this provision is currently unclear. [45] Meanwhile, an independent Investigative Genetic Genealogy Accreditation Board (IGGAB) has organized to develop professional standards, an examination process that will accredit practitioners, and an oversight mechanism to ensure compliance with standards. [4,46] IGGAB is encouraging jurisdictions that require licensure, now and in the future, to adopt its accreditation program as their standard for licensure. [46] If successful, this could help address one objection to mandatory licensure raised by some interviewees: the cost and burden associated with obtaining and maintaining licenses in multiple jurisdictions with different standards and requirements.

The mandatory licensure debate has focused on independent genetic genealogists, but several interviewees in law enforcement observed that in-house expertise with genetic genealogy is growing, and they made role-based and cost-based arguments as to why it makes sense for them to do this work. Given that proficiency is attained from practice and experience, agencies interested in taking the genetic genealogy steps of IGG in-house should consider directing IGG cases to designated personnel, perhaps in specific units, to ensure they have a sufficiently large caseload to hone their skills. In some jurisdictions, this might mean investing in expertise at the state level, which has happened in Florida, [47] Oklahoma, [48] and Wisconsin. [49] But there also might be adequate demand in particular counties and cities, especially if IGG becomes common in active investigations, to justify developing local in-house expertise.

Consistent with the literature, [4] interviewees viewed their ability to use IGG as highly sensitive to public opinion and sought to protect IGG against negative media reports that would, they feared, result in database participants opting out of law enforcement matching or even removing their profiles from the databases, or legislators banning IGG from being used in any investigations. Indeed, perceived public opinion was cited as a reason to support certain guardrails for IGG by those who personally did not believe those guardrails were ethically warranted. Participation in some databases against terms of service was the one practice on which a few—to the dismay of others—indicated a willingness to take their chances with the public.

Many interviewees worried about misunderstanding of IGG and identified points they wished to clarify or emphasize for the public. As more jurisdictions show interest in regulating IGG, practitioners and other experts should consider directing educational efforts specifically to policymakers to help ensure that any regulations they adopt are well informed. Ideally, expert engagement with policymakers will not be a one-time occurrence but instead will take place over time and involve individuals with diverse perspectives on IGG and having expert knowledge and experience across the full range of relevant domains, including IGG practice, criminal law, forensic science, genetic genealogy database operations, genetic privacy, and victim advocacy.

Importantly, the landscape of IGG-relevant regulations is large and includes not only laws specific to IGG but also laws that govern activities adjacent to IGG, such as genetic privacy laws that address responsibilities of genetic genealogy companies vis-à-vis their participants and prohibit certain uses of genetic genealogy databases and information obtained as a result of participating in them. [50] There are many untested complexities associated with application of these laws to various IGG actors and activities, including how these civil code laws interact with criminal code laws and what is their reach given that cases can cross jurisdictional lines and involve data from database participants residing in potentially dozens, if not hundreds, of jurisdictions. Depending on the particular law and regulated activity, the reach can be international, as demonstrated by the EU General Data Protection Regulation’s impact on database approaches to consent for law enforcement matching. [6,17] Moreover, IGG is increasingly an international practice; [14,15] cases have been reported in Australia, [51] Canada, [52] France, [53] Sweden, [24] and Norway. [54] As countries around the world deliberate IGG policy, experts across jurisdictions should share lessons learned with the goal of helping policymakers build and improve on earlier efforts.

This research is subject to limitations. First, our findings do not necessarily reflect the experiences or perspectives of those who did not participate in the study. However, we used a purposive sampling strategy to recruit interviewees reflecting a range of expertise and practice settings. Our sample was also demographically diverse except that, similar to other interview studies, [26] participants predominantly identified as White. Greater racial and ethnic diversity among interviewees may have resulted in additional perspectives not reflected in our data. Given that our sample reflected the demographics of those involved in IGG at the time, this study limitation underscores a broader issue with low racial and ethnic diversity of the field. Second, the data were collected at a specific point in time, and it is possible that participants might respond differently to our questions if interviewed today in light of subsequent professional experiences and industry, practice, and policy developments. Third, given that all participants conducted or facilitated IGG, the data are likely biased towards favorable opinions of IGG. Nevertheless, many participants did not hesitate to express concerns about or directly criticize specific activities.

5. Conclusion

IGG is subject to an increasing number of state regulations, agency policies, and professional guidelines. Regardless of its mechanism, policymaking for IGG should be informed by the diverse groups whose activities and interests are impacted, including, at a minimum, those in the IGG trenches who are using and facilitating the technique. These individuals can help to dispel common misconceptions about IGG and ensure that regulations are based on accurate information about its current practice as well as informed predictions about its future. This, in turn, will help to ensure that IGG policies accomplish their intended objectives and avoid unintended consequences. Empirical studies such as ours that elicit the experiences and perspectives of practitioners and others knowledgeable about the practice of IGG are useful complements to direct engagement with policymakers.