Solving Crimes Through Genetic Genealogy

By Dr. Luis Vaschetto, Ph.D.Reviewed by Lily Ramsey, LLM

Genetic genealogy, the practice of using DNA analysis to trace family trees, has revolutionized the field of criminal investigation. This emerging technique, known as investigative genetic genealogy (IGG), is proving to be a powerful tool in solving cold cases and identifying unidentified remains.

By comparing DNA samples from crime scenes with publicly available genetic databases, investigators can construct intricate family trees and narrow down the pool of potential suspects.

​​​​​​​Image Credit: gopixa/Shutterstock.com

What is Genetic Genealogy?

Genetic genealogy is a relatively new field that combines traditional genealogy research with DNA analysis. By analyzing specific segments of DNA, individuals can trace their ancestry back through generations, identifying distant relatives and constructing detailed family trees. This process involves:

• DNA Testing: Individuals submit DNA samples to be analyzed using specific markers that trace a history wrote in the genetic code.
• DNA Matching: Test results are compared to a database of other individuals' DNA profiles, identifying potential genetic relatives.
• Genealogical Research: Traditional genealogical research techniques, such as family tree records, are used to connect the genetic matches to specific family lines.

Learn more about how DNA analysis has evolved forensics?

How Does DNA Testing Work?

DNA (deoxyribonucleic acid), the genetic material found in every cell of our bodies, is a complex molecule composed of four building blocks: adenine (A), thymine (T), cytosine (C), and guanine (G). These building blocks are arranged in specific sequences, forming genes that determine our traits.

DNA testing for genetic genealogy focuses on different types of DNA:

• Mitochondrial DNA: is a powerful tool for genealogy because it's transmitted from mother to child (i.e., both male and female). This allows researchers to trace a female-line ancestry, or matritrilineal ancestry.
• Autosomal DNA (atDNA): This type of DNA is inherited from both parents and is used to trace ancestry on all sides of the family tree. It is particularly useful for identifying distant relatives through polymorphic genetic sequences.
• Y-DNA: This type of DNA present in the Y chromosome is passed down directly from father to son, allowing researchers to trace paternal lineages.

The Process of IGG

IGG is a powerful tool used in forensic science to identify unknown individuals, such as perpetrators or unidentified remains, by analyzing DNA and constructing family trees. IGG often uses dense single nucleotide polymorphism (SNP) data to infer distant relationships, often beyond first cousins, to identify suspects or missing persons¹.

This approach has already been successfully utilized to identify two distant relatives who matched the crime scene samples, leading to the conviction of a murderer².

IGG involves several key steps:

1. DNA Collection and Profiling. DNA is collected from a crime scene, and a profile is created using Single Nucleotide Polymorphism (SNP) microarray analysis. This profile includes dense SNP data, often over half a million SNP markers^1,3.
2. Uploading DNA Profile to Public Databases. The DNA profile is uploaded to public genetic genealogy databases, such as FamilyTreeDNA⁴. These databases allow individuals to upload their DNA profiles to research their family history.
3. Identifying Genetic Matches. The uploaded DNA profile is compared to other profiles in the database to identify potential genetic matches.
4. Genealogical Research to Identify Potential Suspects. By analyzing the family trees, investigators can identify potential suspects who share a genetic link to the DNA evidence⁵. This can narrow down the pool of potential suspects and help focus investigative efforts.
5. Traditional Investigation. Once potential suspects have been identified, traditional investigative techniques, such as surveillance, interviews, and search warrants, can be used to gather additional evidence. This can lead to arrests and prosecutions.

The impact of ethics in forensics

Public DNA Databases: A Double-Edged Sword

Public DNA databases have become a cornerstone of genetic genealogy and, therefore, also IGG, enabling, in the first case, individuals to connect with distant relatives and uncover their family history, and in the second case, law enforcement agencies to identify potential suspects and solve crimes.

These databases facilitate the discovery of long-lost relatives and the construction of detailed family trees. However, the accessibility of these databases also presents a risk, raising ethical concerns about privacy, security, and potential misuse. The main risks associated with public DNA databases include:

• Privacy Concerns: Sharing genetic information with a public database raises concerns about potential privacy breaches and the misuse of personal data⁶.
• Genetic Discrimination: There is a risk of discrimination based on genetic predispositions to certain diseases or conditions⁷.

Challenges and Perspectives of IGG

IGG has emerged as a powerful strategy in criminal investigation, revolutionizing the way cold cases are solved, and unidentified remains are identified. By analyzing genetic information, IGG has the potential to provide critical breakthroughs in cases that have long defied solutions.

However, the ethical implications and legal challenges associated with this technology cannot be ignored. As IGG continues to evolve, it is imperative to strike a delicate balance between its immense potential and the need to safeguard individual privacy and ensure its responsible application.

By carefully considering the regulatory ramifications and implementing robust legal frameworks, we can harness the power of IGG to bring justice to victims and their families while upholding the principles of fairness and human rights.

References

1. Vries, J., Kling, D., Vidaki, et al. (2021). Impact of SNP microarray analysis of compromised DNA on kinship classification success in the context of investigative genetic genealogy. bioRxiv. https://doi.org/10.1101/2021.06.25.449870.
2. Tillmar, A., Fagerholm, S., Staaf, J., Sjölund, P., & Ansell, R. (2021). Getting the conclusive lead with investigative genetic genealogy - A successful case study of a 16 year old double murder in Sweden. Forensic science international. Genetics, 53, 102525. https://doi.org/10.1016/j.fsigen.2021.102525.
3. Ertürk, M., Fitzpatrick, C., Press, M., & Wein, L. (2022). Analysis of the genealogy process in forensic genetic genealogy. Journal of Forensic Sciences, 67, 2218 - 2229. https://doi.org/10.1111/1556-4029.15127.
4. Kennett, D. (2019). Using genetic genealogy databases in missing persons cases and to develop suspect leads in violent crimes. Forensic science international, 301, 107-117.
5. Greytak, E., Moore, C., & Armentrout, S. (2019). Genetic genealogy for cold case and active investigations. Forensic science international, 299, 103-113 . https://doi.org/10.1016/J.FORSCIINT.2019.03.039.
6. Miller, S., & Smith, M. (2022). Quasi-Universal Forensic DNA Databases. Criminal Justice Ethics, 41, 238 - 256. https://doi.org/10.1080/0731129X.2022.2141021.
7. Wauters, A., & Hoyweghen, I. (2016). Global trends on fears and concerns of genetic discrimination: a systematic literature review. Journal of Human Genetics, 61, 275-282. https://doi.org/10.1038/jhg.2015.151.

Further Reading

• All Forensics Content
• Collecting Evidence at a Crime Scene
• Using Forensics to Tackle Child Exploitation
• Forensic Investigations of Natural Disasters
• Forensic Identification in Mass Disasters